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Series 
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microfiches 
(monographies) 


Canadian  Institute  for  Historical  Microreproductions  /  Institut  canadien  de  microreproductions  historiques 


Technical  and  Bibliographic  Notes  /  Notes  techniques  et  bibliographiques 


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D 


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I I    Coloured  maps  /  Cartes  geographiques  en  couleur 

I       I    Coloured  ink  (i.e.  other  than  blue  or  black)  / 


□ 


n 


n 


Encre  de  couleur  (i.e.  autre  que  bleue  ou  noire) 

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n 
n 


This  item  is  filmed  at  the  reduction  ratio  checked  below  / 

Ce  document  est  filme  au  taux  de  reduction  indique  ci-dessous. 


lOx 


14x 


18x 


22x 


71 


26x 


30x 


12x 


16x 


20x 


24x 


28x 


The  copy  filmed  here  has  beer  .eproduced  thanks 
to  the  generosity  of: 

Engineering  Sciences  Library 
Queen's  University 


L'  exemplaire  filme  fut  reproduit  grace  a  la 
generosite  de: 

Engineering  Sciences  Library 
Queen's  University 


This  title  was  microfilmed  with  the  generous 
permission  of  the  rights  holder: 

Forbes  la-i  Rickard 


Ce  titre  a  ete  microfilme  avec  I'aimable  auforisation 
du  detenteur  des  droits: 

Forbes  Tad  Kickard 


The  images  dppearir-  "lere  are  the  best  quality 
possible  considering  >,  e  'ondition  and  legibility  of 
the  original  copy  and  in  k.    ^ir,g  with  the  filming 
contract  specifications. 

Original  copies  in  printed  paper  covers  are  filmed 
beginning  with  the  front  cover  and  ending  on  the 
last  page  with  a  printed  or  illustrated  impression,  or 
the  back  cover  when  appropriate.  All  other  original 
copies  are  filmed  beginning  on  the  first  page  with  a 
printed  oi  illustrated  impression,  and  ending  on  the 
last  page  with  a  printed  or  illustrated  impression. 


The  last  recorded  frame  on  each  microfiche  shall 
contain  the  symbol  -^(meaning  "CONTINUED  ),  or 
the  symbol  V  (meaning  "END"),  whichever  applies. 

Maps,  plates,  charts,  etc.,  may  be  filmed  at 
different  reduction  ratios.  Those  too  large  to  ^e 
entirely  included  in  one  exposure  are  filmed  begin- 
ning in  the  upper  left  hand  corner,  left  to  right  and 
top  to  bottom,  as  many  frames  as  required    The 
following  diagrams  illustrate  the  method: 


1 

2 

3 

Les  images  suivantes  ont  ete  reprodnites  avec  le 
plus  grand  soin,  compte  tenu  de  la  condition  et  de 
la  nettete  de  I'exemplaire  filme,  et  en  conformite 
avec  les  conditions  du  contrat  de  filmage. 

Les  exemplaires  originaux  dont  la  couverture  en 
papier  est  imprimee  sont  filmes  en  commen^ant 
par  le  premier  plat  et  en  terminant  soit  par  la 
derniere  page  qui  comporte  une  empreinte  d'im- 
pression  ou  d'illustration,  soit  par  le  second  plat, 
selon  le  cas.  Tous  les  autres  exemplaires  origin- 
aux sont  filmes  en  commen^ant  par  la  premiere 
page  qui  comporte  une  empreinte  d'impression  ou 
d'illustration  et  en  terminant  par  la  derniere  page 
qui  comporte  une  telle  empreinte. 

Un  des  symboles  suivants  apparaitra  sur  la 
derniere  image  de  chaque  microfiche,  selon  le  cas: 
le  symbole  ^  signifie  "A  SUiVRE",  le  symbole  V 
signifie  "FIN". 

Les  cartes,  planches,  tableaux,  etc.,  peuvent  etre 
filmes  a  des  taux  de  reduction  differents.   Lorsque 
le  document  est  trop  grand  pour  etre  reproduit  en 
un  seul  cliche,  il  est  filme  a  partir  de  I'angle 
superieur  gauche,  de  gauche  a  droite,  et  de  haut 
en  bas,  en  prenant  le  nombre  d 'images 
necessaire.   Les  diagrammes  suivants  illustrent  la 
metiiode. 


1  2  3 

4  5  6 


MICROCOPY    RESOLUTION    TEST    CHART 

ANSI  end  ISO  TEST  CHART  No    2 


1.0 


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THE 


FLOTATION    PROCESS 


Compiled  and  Editea 

by 

T.  A.  RICKARD 


FIRST   EDITION 


Published   by   the 

MINING  and  Scientific  PRESS 

San  Francisco 


,' Jrl  -) 

.---'•--- 

T  IN  6  'i.  ^  .  r(  C 


('(iri  iiii.H  r.  r.iHl, 

iiv 

Dkwky   !'i  III  i-~iitno  Co. 


-!i^ 


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PREFACE 

Tliis  li(«ik  liiis  hii'ii  |in'(nin'il  to  mt'ct  tin-  iicid  cil'  the  lionr.  1-  Intii- 
tioii  is  I'MjjuKiiitr  tlif  alU'iitioii  of  ii  rapidly  iiicrcasiiin  iiiiiiiIm  i  (if 
inctalliirgists,  iiiillinoii,  and  iiiiiie-owiit'rs.  In  format  ion  on  the  Hntijcct 
i>  liirkiii^r.  'I'ln'  only  hook  lierotoforo  issued  was  written  four  years 
ago,  and  is  now  out.  of  date.  In  V.)\2  tlie  flotation  proeess  had  hardly 
won  a  foothold  in  the  I'nited  States;  today  fully  oO.OOO  tons  of  ore  is 
heiiKj  treated  daily  by  the  frotliinp  or  bubhle-Ievitation  method.  In 
July  l!*!;")  the  Mining  ami  Scii  ntific  I'n  ss  hr(;aii  to  pnhlish  a  series  of 
artieles  desorihing  eurrent  progress  in  this  new  hraneh  of  metallurgy. 
These  were  followed  tiy  a  nuinher  of  interesliiiff  eontrihutions  on  the 
theory  of  the  snlijeet.  All  of  them  are  reproduced  in  this  volume. 
Tliey  elaim  no  finality.  The  physics  of  flotation  is  .still  a  riddlf  un- 
solved; but  the  betrinnings  of  investination  have  been  made.  In  the 
pages  that  follow  will  be  found  Uie  rudiments  of  a  connected  theory 
explaining  the  phenomena  underlying  the  life  and  activity  of  the 
metallurgic  bubble. 

In  preparing  this  volume,  I  am  under  plejisant  obligation  to  the 
various  contributors;  it  will  not  be  deemed  invidious  if  I  express 
special  indebtedness  to  Messrs.  0.  C.  Ralston.  ('.  T.  Durell.  Dudley  H. 
Norris,  and  Will  II.  Coghill.  The  reader  will  be  particularly  grateful 
to  Mr.  Ralston,  of  the  U.  S.  Bureau  of  Mines,  for  his  invaluable  article 
on  the  testing  of  ores  by  flotation  and  for  his  resume  of  preferential 
methods.  Messrs.  Durell.  Norris.  and  Coghill  have  helped  to  clarify 
many  obscure  points.  To  the  anonymous  metallurgist  who  wrote  on 
the  experiments  at  the  Mexican  mill  an<l  on  the  effects  of  soluble  salts, 
I  tender  special  thanks;  also  to  Messrs.  Butters  and  riennell  for 
their  detailed  account  of  experimental  work  on  flotation  concentrate. 
To  all  of  these  and  to  the  other  contributors.  I  extend  my  hand. 

T.  A.  RiCK.'.Ri). 
Editor  of  the  Minin<i  and  Stit  n!ific  Pnsn. 
San  Francisco.  March  1.  1016. 


|1>^25B 


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H.^r' 


I 


,>-V-_..-:. 


lABI  E  OF"  CON  I  tlN  TS 


Pbkp. 


A  (iloxsaiN   of   Fliiiiiliiiii    

The  Kloliilion   I'kkohh ''■.  .1.   Uirknul 

Klotatioii  Ttsts  al    Moiiiit    Moikhii Ui.7ir;m    Mothiriirtl 

Oils   I'setl   ill   llii-   Klotiilidii    I'rofcsrt    DrnniDiidl  Cnnlnlnitur 

Klotiilion   (if   Ciiiip*'!    Oi'^x    •'     W.    <'"I'"U- 

IT.lVrcntial   Kloiaiioii   "■  '"    Hnhton 

Kldtali 1    111''   liis|iiratii)ii  Mine,  Arizona ■WinCim   Mulhrruit' 

Hdialloii   ill  a  N.cxicaii   Mill .s'/"'''"'  ('"rnsix'iiihni 

Kioih  and  I'lotalion.  .  .  .  \V.  /■'.  C'>iiiUuiil.  Dnny  lliitlrr,  (DuI  Jus.  if.  W'lxr 
Klolalion  at  WmhIioc  Hcdiictlon  WorUs,  Anaconda  /•-'    /'■  .Uathrirsun 

Flotation  at   the  Cj-iitral   Miiir,   HidUimi   Hill ./(/mi  ,  Ihhhnnl 

What  iH  Flotation?-  1 T.  A.   Hvknnl 

\Vh>     is    Flotation?-    I CliiirU:i    T     Diinll 

What  is  Flotation?— II T.   ,1.   Hi'knnt 

Surfare  Tension  and  Salts  in   Solution Will   If.   i'lmfnU 

Air-Froth    Flotation  -I "'     •'•    ^''"" 

Why   Do  Minerals  Float? Olinr  c.   fx'dlstoii 

Why    Is   Flotation''  — II ./<nnr.i   .i.   fllmk 

Ail-Froth   Flotation— II //-  "     WiUiiuji-i  'inil   W.  If.  Kriiijnn 

Cyaiiiiie  Treainieiit  of   Flotation  Concentrate    

CharU's  Biiltrrn  ami  J.  A,'.   Cliinii'll 

Flotation  on  Cold  Ores   -l-  f--  I>rink'r 

The  Klectrical  Theorv  of  Flotation— I Thomas  .V.  lininn.  .Ir. 

/.  .u.  r.i/;o»- 


Notes  on   Flotation    

Dis|iosal  of  Flotation  Residue "'■  slirllslir.ir 

Th"  Klectrical  Theory  of  Flotation— II Thoiiuis  M.  lUiiiis.  .Ir. 

Fffects  of  Soltihle  Coniponetits  of  Ore  on  Flotation 

Occd.s-io/m!  ('iirr<  sixindi'iit 

Flotation — \   I'ar:i(lox    t)ii<lliU  If.   Xorris 

Flotation  of  Go'.d  Ores  Charles  Buttcr.s 

TestiiiK  Ores  for  the  Flotation  Process— I 

0.  C.  Itahton  awl  GU'im  L.  AlUn 
Testiim:  Ores  for  the   Flotation   TrocesH— II 

0.  C.  Halston  ami  (ilfiiii  h.  Allen 

Mole(  \ilar  Forces  in  Flotation Dudley  If    Xorris 

Flotation-Tests  In  Separating  Funnel   Special  Correspondent 

Flotation  Principles  C-  T^rry  Durell 

The  Electro  Statics  of  Flotation f-  A.  Fahremcahl 

On  the  Science  of  a  Froth Wi"  H.  CofihiU 

Smeltinc;    Flotation    Concentrate    

Flotation  on    Dump  Ore    V.   F.   Stanley   Loir 

Simple  Problems  in  Flotation T.   4.  fficcant 

Index    


7 
'J 

i:o 
li'i 
71 
S3 

m 

iiij 

inti 

110 

1-ji; 
1,;.'. 
lit 
i:.t 

Kill 

17.". 

1^7 

is;i 
2n:! 

L':;i 
2113 

JtM 

27fi 


293 
30S 
31 S 
319 
335 
344 
351 
354 
35f. 
3G1 


I,.^- 


A  GLOSSARY  OF  FLOTATION 

AnsoKH.    To  drink  in,  siirl;  up,  like  a  siionge. 

AiisnriB.  To  condense  and  hold  a  gas  on  the  surface  of  a  solid,  particu- 
larly metals.     From  L.  nd.  to.  ami  norheo.  suck  in. 

AdiTATio.N  is  the  act  or  state  of  being  shaken,  stirred,  or  moved  with 
violence.     From   L.  apitatus.  aaito.  the  freciuent  of  ag<i.  to  drive. 

B.MKi.K.  That  which  defeats  or  frustrates,  lunce  the  i)rojections  or 
wings  that  dive.t  or  interrupt  the  flow  of  pulp  in  a  vessel. 

Briiiii.K.  A  .L'lohule  of  air  or  other  gas  rising  in  a  liquid;  also  a  vesicle 
of  water  or  other  liquid  inflated  with  air  or  other  gas. 

lUov.     To  kee|>  from  sinking,  to  keep  afloat  in  a  liquid. 
Co.M.r.Mi   is   a   thick,   black,   viscid,   and    opaque    liquid   condensed    when 
gas  is  distilled   from   coal.     Such   i>roducts  consist   of  soluble  and   insoluble 
substances. 

Co.\c,ii,ATioN.  The  state  of  a  liquid  resulting  from  clotting  or  curdling, 
the  act  of  changing  to  a  curd-like  condition. 

CoNtKNTR.\TK.  To  draw  or  gather  together  to  a  common  centre.  To  re- 
duce to  a  purer  state  by  the  removal  of  non-essential  matter.  From  L.  ron 
or  cum,  with,  and  centrum,  a  centre. 

Co.NT.\MiN.\TK.    To  make  Impure  by  contact  or  admixture. 
Er.KiTBO-sT.\Tics.     That  branch   of  electrical  science   devoted   to  ihe   phe- 
nomena of  electricity  at  rest  or  of  frictional  electricity. 

Kmii.sion.  Milkification.  A  liquid  mi.Kture  in  which  a  fatty  or  resinous 
substance  is  suspended  in  minute  globules.  From  L.  rmuJiio.  to  drain  out, 
in  turn  from  r.  out,  and  mulgco.  milk. 

Efc.M.Yi'Tis  on..  The  oil  distilled  from  one  of  the  Australian  gum-trees, 
the  cutnlyptus  amyijdaUna. 

Fat  is  a  white  or  yellowish  substance  forming  the  chief  part  of  adipose 
tissue.     It  may  be  solid  or  liquid;   it  is  insoluble  in  water;    when  treated 
with  an  alkali,  the  fatty  acid  unites  with  the  alkaline  base  to  make  soap. 
Film.    A  coating  or  layer,  a  thin  membrane. 

Fi.odii.KNT  means  resembling  wool,  therefore  woolly.  Coalescing  and 
adhering  in  Hocks.  A  cloud-like  mass  of  i)recipitate  in  a  solution  From 
I.,  floctus,  a  lock  of  wool. 

Flotation  is  the  act  or  state  of  floating,  from  the  French  fluttnUiov. 
water-line,  and  fluttir.  to  float,  to  waft. 

Fr.oiATioN-KKKi).  The  crushed  ore.  jiulp,  or  other  mill-product  that  goes 
for  treatment   to  the  flotation  plant. 

FiioTit.  A  collection  of  bubbles  resulting  from  fermentation,  efferves- 
cence, or  agitation. 

Ganci  K.  The  non-metalliferous  or  non-valuable  metalliferous  minerals 
In  the  ore;   veinstone. 

(iRAMiAiuiN  is  the  state  or  process  of  being  formed  into  grains  or  small 
Ijarliiles.     From  L.  granum.  a  grain. 

C.iUAsi:.  Animal  fat  when  soft.  Also  anything  oily  or  unctuous.  From 
the  French  graisse. 

I.EMT.vTioN.     The  act  of  rendering   light   or  buoyant.     L.   h-vitnit.   light- 


Metai.i.ic.     Of  or  belonging  to  metals,  containing  me*.  Is,  r.  ore   particu- 


larly  the  valuable  nipfals  that  are  the  oliject  of  mining.  Kroni  I.,  nifl'illinn. 
ore. 

MiNKKAL.  Iiiornaiilc  constinient  of  the  earth's  crust.  A3  used  in  flota- 
tion the  terms  iiiineral'  or  'metallic'  iiarticles  hark  bark  to  the  French 
(miHOdi,  ore!  and  S|ianish  {jhetal,  ore)  meanings.  Both  terms  refer  lo 
those  valuable  constituents  in  the  ore  that  it  is  tho  object  of  the  process  to 
separate  from  the  non-valuable  constituents,  or  gangue.  Sometimes  'metal- 
lic' has  reference  to  metallic  lustre,  one  of  the  chief  characteristics  of 
metals  and  more  particularly  of  those  metallic  sulphides  that  are  especially 
amenable  to  flotation. 

.MipMiKv.     To  change  in  character  or  properties. 

Mcii.K.(  I  i.K.  The  smallest  part  of  a  substance  that  can  exist  separately 
and  still  retain  its  composition  and  characteristic  properties:  the  smallest 
combination  of  atoms  that  will  form  a  given  chemical  cunipoiind.  From  F. 
viiih'i  iilr.  diminutive  from  L.  iiioU's,  mass. 

N.v.sctNT.  Coining  into  licing,  beginning  to  develop.  From  L.,  /uisicns. 
being  born. 

Oi  cii  iiK.  To  shut  or  close  pores  or  other  oi)enings.  From  1...  ob.  before, 
claudu.  close. 

Oil  ic  .\i  11)  is  fatty  acid  contained  in  olive  oil  combined  with  cresoliue. 
zMtlioimh  called  'acid'  it  is  an  oily  substance  and  functions  as  oil  in  flota- 
tion operations;  it  is  contained  in  most  mixed  oils  and  fats,  from  which  it  is 
obtained  by  siiponitication  with  an  alkali.     From   L.  nh-iun,  oil. 

On,  includes  (ll  fatty  oils  and  acids,  (2)  essential  oils,  luoslly  of  vegetal 
origin,  such  as  eucalyptus  and  iurpentin'\  (3)  mineral  ous,  such  as 
pell  oleum   products,   including  luliricating  oils, 

Oii.v  and  Gkk.vsv  are  sulistaniially  equivalent  terms.  .-\11  oils  are  greasy. 
Greasiness  suggests  more  viscidity  than  oiliiiess. 

Os.\io>K.  The  tendency  of  two  liquids  or  gases  to  mix  by  passing  through 
a  membrane  or  porous  wall  separating  them.     From  O.  osinos.  pushing. 

FiM.oii,  is  a  derivative  of  wood-tar,  as  phenol  and  cresol  are  derivatives 
of  coal-tar. 

Piir  is  powdered  ore  mixed  with  water. 

S.M'dMiu MioN,  Conversion  into  soa|i;  the  process  in  which  fatty  sub- 
stances form  soap,  by  combination  with  an  alkali.     From  L.  xnpu  (n-),  soap. 

Set  \i.  Imjnire  or  extraneous  matter  that  rises  or  collects  at  the  surface 
of  liquids,  as  vegetation  on  stagnant  water,  or  dross  on  a  bath  of  molten 
metal. 

Ski.n.     All  outside  layer,  coat,  or  covering.     From  A.  S.  siiiui,  ice. 

Si'ir/K  \siKN.  A  iioiiited  box  or  inverted  iiyiamidal  vessel,  with  an  out- 
let at  its  point  for  the  separation  of  the  components  of  an  ore  by  gravity. 
German,  spitze.  point,  ktistcii.  chest. 

SiRK.vtK  TK.Nsiu.N  IS  the  contractile  force  tit  the  surface  of  a  liquid  where- 
by resistance  is  offered  to  rupture. 

Vksici  K.  A  sn'all  bladdei-lik.  cavity  or  hollow  sphere  of  liijuid.  From 
rcsicM/d,  diminutive  from   icsici.  bladdt-r. 

VisKisrrv  is  the  property  of  lioiiids  that  causes  them  to  resist  i'l^tan- 
taneous  change  of  tlieir  shape  or  of  the  arrangements  of  their  jiarts;  inurual 
friction:    guniminess.     l'"rom  1..   its(tiiii.  birdlime. 


THE   FLOTATION   PROCESS 

By  T.  A.  RicKAKii 
(From  the  Miniiiij  and  ^rirntiftc  Pre.si  of  Maroh  4,  IS,  and  April  1,  19U!) 

•Inteoductory.  It  is  not  yet  four  years  since  the  starting  of  the 
first  American  mill  using  the  frothing  method  of  flotation,  yet  55,000 
tons  of  ore  is  being  treated  daily  hy  tills  process  in  the  Unitod  States 
today.  This  means  20,000,000  tons  per  annum.  Tiie  larger  part  of 
these  metallurgical  operations  began  within  the  last  two  years.  It  is 
evident  therefore  that  the  process  is  gaining  ground  so  rapidl,v  as  to 
command  the  intelligent  attention  of  all  thoso  engaged  in  mining. 
In  the  present  writing  upon  the  subject  I  have  tried  to  supply  suen 
information  as  is  required  by  those  newly  interested  in  flotation, 
I'ither  as  students  or  as  operators.  Of  {•ourse.  what  I  have  written 
makes  no  claim  to  finality,  for  I  am  conscious  of  possessing  only  an 
elementar.v  understanding  of  the  exiremel.v  abstruse  set  of  phenomena 
underlying  the  process.  'My  contribution  is  that  of  a  detached  ob- 
server, eager  to  be  helpful  to  the  workers  in  tins  new  branch  of 
nietallurg.v. 

TiiK  Physics.  In  a  recent  reminiscence  my  friend  Ren  Stanley 
Kevett  has  recorded'  how  he  bet  "a  bottle  of  bubbles"  with  that 
pi'rii)atetic  philosoplier  Thomas  F.  Criley,  the  partner  (•(  Carrie  Jane 
Hvcrson  in  an  oil  process  of  concentration  whereby  the  valuable  sul- 
phides were  made  to  flo;it  above  the  worthless  gangiie  in  a  pulp  of 
cru.'ilH'd  ore.  JFr.  Revett  .says  tliat  he  bet  liis  Inibbles  against  ('rih'.v's. 
but  we  suspect  that  in  saying  so  he  was  interpreting  the  prior  art  in 
terms  of  latter-day  me1allurg,v.  for  it  is  doulitful  whether  any  of  the 
persons  concerned  in  tliiit  early  experiment  at  Raker  City.  Oregon, 
had  a  clear  understanding  of  the  function  of  the  bubbles  in  assisting 
tile  oil  to  give  ])uo,vjiiie,v  to  tlie  sul])hides.  However,  in  staking  bis 
biibliles  of  enrhon  dioxide  dissolveci  under  i>ressure  in  the  vintage  of 
Chaniiiagne  against  the  performance  predicated  bv  Crile.v,  Jlr.  Revett 
must  be  credited  with  su(>cessful  anticipation,  fcir  27  yenrs  after  the 


•This  article  wa.=;  jiresfnted  as  a  paper  at  the  March    (Ifllfil   meotiiiR  of 
the  Caiiaflian   Miiiinc  Institute. 

'Mhi:>i(/  ami  Krimtifir  Pri'ss.  October  Ifi,  1915. 

9 


10 


THE    FLOTATION    PROCESS 


incident  we  know  that  the  key  to  the  flotation  process  is  to  lie  found 
not  in  the  oil,  the  acid,  or  the  apparatus,  hut  in  the  bulihlcs. 

The  man  who  understands  the  physics  of  a  soap  hutiMe  has  mas- 
tered the  chief  mystery  of  flotation.  The  small  boy,  who.  as  pictured 
by  ]\lillais.  watches  the  iiirth.  a.scent,  and  bursting  of  the  iridescent 
si)here  of  his  own  making,  is  the  type  of  our  modern  metallurgist  who 
makes  the  multitudinoiis  bi.iibles  constituting  a  froth  and  then  won- 
ders to  what  laws  of  physics  this  tilmy  product  owes  its  existence. 

To  i)Ut  it  bi'iefly.  the  boy.  liaving  dis.solved  soap  in  water,  Imhls  a 
little  of  it  in  the  bowl  of  his  elay  pipe  while  he  blows  through  the 
stem.  'J'ue  soa])y  water  forms  a  film  that  is  distended  by  the  boy's 
warm  lireath  into  a  lively  sphere,  which  is  lighter  tlian  the  surround- 
ing air  and  therefore  rises,  while  the  sunshine  undergoes  refraction 
into  the  colors  of  the  spectrum.  When  the  boy  blows  through  iiis 
pipe  into  i)uri_  water,  he  makes  l)ubbles  likewise,  liut  ilic.v  lu'cak  in- 
stantly. It  is  the  soap  that  lengthens  their  life.  In  the  language  of 
physics  we  say  that  higli  'surface  tcTisiou'  causes  tlie  pure-wafer 
bubbles  to  burst  immediately,  while  the  addition  of  soap  introduces  a 
contaminant  that  lowers  the  tension  so  as  to  enable  the  bul)hles  to  last 
longer. 

The  basic  factor  in  the  making  of  l)ulibl(>s  is  surface  tension.  This 
is  the  force  that  causes  the  surface  of  a  liquid  to  resist  mpturc.  The 
particles  at  the  surface  liave  a  greater  coherence  than  the  similar  par- 
ticles within  the  body  of  the  licpiid.  In  other  words,  each  molecule 
within  the  interior  of  tlie  liquid  may  be  pictured  as  surrounded  by 
molecules  like  itself  in  being  attracted  toward  each  other  e(|ually  in 
all  directions:  while  the  molecules  at  the  free  surface  of  the  liquid 
are  aitraeted  only  by  those  internal  to  themselves,  the  result  being 
to  constrict  the  free  surface  to  the  least  area.  In  consequence,  the 
sui-face  acts  as  if  it  were  elastic.  Hence  the  attachment  of  water  to 
the  sides  of  a  tube  and  the  drawing  nf  that  water  uj)ward — which  is 
called  •capillarity'  because  it  is  most  marked  in  a  tube  as  small  as 
rapilJii'^.  a  liair. 

Numerous  manifestations  of  surface  tension  on  wafer  could  be 
cited.  Fill  a  tumbler  a  little  nn  iv  than  full  and  the  water  will  have  a 
convex  surface,  indicating  that  there  is  some  force  at  work  to  preve;il 
the  w.'ifer  from  spilling.  Note  the  cohesion  between  two  plates  that 
have  been  wetted.  Dip  a  camel '.s-hair  brush  into  water  and  the  hairs 
■■W;.^  jf,^^.i!.{.5=.  inimcrse  the  -"-t  ^ru=h  in  the  wntrr  rsrid  ttm  !;:!!•■'. 
sejiarate  Wafeli  tlie  formation  of  a  drop  of  vcater  and  Tiote  flial  it 
tiehaves  as  if  envelo])ed  by  a  stretched  membrane.    Water-spiders  can 


THE    FLOTATION    PROCESS 


11 


be  soon  niiiiiiiig  over  tlie  surface  of  a  pond  in  summer,  as  small  boys 
run  over  a  jximi  covered  with  i<-e  iu  winter.  The  ice  bends  under 
their  weifrht  witliout  lircdking;  so  also  the  spider-  makes  a  visible 
dimple  without  wetting  his  feet.    The  surface  is  not  ruptured. 

The  force  of  surface  tension  has  been  measured  by  ascertaining 
the  weight  that  can  be  suspended  from  a  lilm  of  water  in  air.-^  It  has 
been  stated  as  3}  grains  per  inch'  or  81  dynes  per  centimetre.'  The 
most  recriit  determination  is  tliat  of  Iheodore  W.  Pichards  and  Leslie 
B.  ("oombs.''  who  found  it  to  be  72.62  dynes  per  cei  in'c're  at  20''C. 
Many  disturbing  factors  enter  into  the  me;  urement  of  this  force,  so 
that  divers  figures,  ranging  from  70.6  to  81,  have  tieen  announced  at 
different  times. 

Surface  tension  ditTers  as  between  various  liquids  and  fluids  in 
contact  ;  for  example,  the  tension  separati'-.g  mercury  from  water 
amounts  to  418  dynes  per  centimetre,  while  that  separating  olive  oil 
from  air  is  only  1)6. !l  dynes.  A  drop  of  pure  water  will  spread  over 
the  surface  of  pure  mercury  as  oil  will  spread  over  water.  The  sur- 
face tension  of  an  oil-water  surface  is  only  14,  as  compared  with  the 
7.'i  of  an  all-water  surface  at  a  temperature  of  18''C.'  While  the 
film  of  oil  on  water  may  be  only  one  molecule  tliiek,  or  one  twenty- 
five  millionth  of  an  inch,  it  will  s'.iffice  to  reduce  the  etTective  pull  of 
the  water  surface  from  73  to  43.  This  latter  figure  represents  the 
efTectivc  surface  tension  of  water  modified  by  oil  as  used  in  flotation. 
It  is  the  main  factor  in  the  formation  and  persistence  of  a  bubble. 
Heat  lowers  the  surface  tension  of  water.  Place  powdered  sulphur 
on  the  surface  of  the  water  on  a  horizontal  plate  of  clean  metal :  apjily 
heat  locally:  the  sulphur  is  pulled  away  by  the  old  liquid  a.s  against 
the  feebler  tension  of  the  warmer  liqiiid. 

This  elastic  force  at  the  surface  of  a  liquid  tends  to  draw  it  into 
the  most  compact  form.  That  is  why  a  drop  assumes  the  form  of  a 
.spiiere.  in  which  sliapc  it  presents  the  smallest  surface  in  relation  to 
its  volume.  Surface  tension  is  a  contractile  force.  This  is  shown 
in  a  simpl.'  way  by  blowing  a  soap  Imbblc  on  the  large  end  of  a 
pipe  and  then  liolding  the  other  end  of  the  pipe  to  a  candle, 
when    the    air    es^.iping    from    the    shrinking    bag    of    the    bubble 


2ln  N'pw  Knglaud  the  boys  call  them   sknters.' 

•TA  Text-Rook  of  the  F-rinciples  of  Physics.'     By  Alfred  nanniell,  1911. 
<r.  V.  Boys  in  'Soaji  Bubbles.' 

■■'Clerk  Maxwell   in  the   Ent  iiclDpndin   Brilnr.iiun.   under  'Capillarity.' 
'TiiH  Siirfact'  Tension  or    walcr,  Alcohols,  etc.       lour.  Amrr.  Cue   i.  .soc, 
.Tilly  mir,, 

"'A  Text-Book  of  Physics.'    By  .T.  H.  PoyntinK  and  .1.  .1.  Thomson,  191.1, 


12 


TliZ   FLOTATION    PROCESS 


extingniishcs  tlie  Haim".  as  id  Fifr.  1.*  Wlicii  water  is  spilled 
on  a  stove,  it  (ussniiies  a.  ^.'lobular  fdrtn  and  dances  on  the  hot 
iron  until  it  flashes  into  steam.  When  water  is  sprinkled  on  a  dusty 
floor,  the  dust  forms  a  layer  upon  the  drop  of  water,  wliioh  draws 
itself  tocrethcr  into  rollinfr  spherules.  The  smallest  drops  are  the 
most  nearly  round;  in  the  larger  ones  the  weight  causes  a  flattening, 
because  gravity  overcomes  the  elasticity  of  the  surface  film.     That  is 


FlO.    1.      THE   CONTBACTI.no   BUBBLE   BLOWS   THE   FLAME. 

shown  even  more  clearly  in  the  case  of  drops  of  mercury,  and  i)y  the 
beads  of  gold  on  an  assayer's  cupel. 

This  contractile  force  at  the  surface.  wherel)y  a  portion  of  liipiid 
gathers  itself  together  into  splu'rical  form,  explains  why  the  pure- 
water  ])ubMe  liursts  so  readily.  The  hitrh  tension  shatters  it.  It  does 
not  burst  ex[)h)sively.  by  expansion  of  the  gius  within  the  envelope, 
hut  by  lateral  displacement  of  the  substance  of  the  elastic  film.  It 
collapses  because  the  surface  tension  draws  it  together.  To  prevent 
such  immediate  colhi])se  it  is  necessary  to  lessen  the  tensio",  that  is. 
diminish  the  contractile  force  in  the  ela.slic  mcudirane  constituting 
the  film  (if  the  bubble.  This  can  be  done  by  introducing  an  imp\irity 
or  coidaminant.  which  lowers  the  surface  tension,  that  is.  diminishes 
the  (Minlraciibility  nf  th.-  bubble-lilm.  AVatcr  has  llie  highesl  surface 
tnisidu  of  any  commdti  liquid  excejit  nienMiry.  sn  th.-d  the  addition 
of  aiKitlier  liiiuid  usually  l.)wers  its  surface  tension. 

Oil  in  euudsiiiii  and  organic  substances  in  solution  can  be  use<l  for 
tins  purpose.     Soap  will  have  flie  same  effect,  and  that  is  why  a  sciaj) 

*C.  V.  nnys  in  'So.ip  nn!)blps.'  pace  49. 


THE    FLOTATION    I'ROCESS 


13 


liiilihlc  lasts  Ioniser  tliaii  a  piirt'-watcr  liuhhlc,  Wu-  tiliii  nt'  the  t'oniuT 
(•i)Msi.stiii<:c  <»l'  water  liaviiij;  some  soap  in  solution.  Wlien  water  has 
been  modified  by  sueh  a  eontaniinant,  the  components  of  the  Him  can 
so  dispose  themselves  that  the  superficial  forces  will  he  the  same 
everywhere,  that  is.  tend  to  remain  in  eqiiilitirium,  includinii^  the  force 
of  gravity,  wh'ch  otherwise  would  pull  the  film  apart. 

When  two  bubbles  come  in  contact  they  tend  to  coalesce  because 
file  two  of  them  have  an  agfrre<i:ate  area  greater  than  thai  rcfpiired 
to  include  the  same  amount  of  air  within  a  single  bubble,  fn  pure 
water  the  bubbles  coalesce  with  a  violence  that  is  nnitually  destruc- 
tive. Kven  when  a  survivor  is  left,  the  violence  of  coalescence  of  such 
bubbles  in  a  pulp  unhorses  any  mineral  particles  that  may  be  riding 
the  bubbles.  When,  however,  the  water  is  modified  by  oil,  the  con- 
tractile force  of  surface  tension  is  diminished,  the  bubbles  are  less 
fragile,  and  they  survive  long  enough  to  perform  their  metallurgical 
duty  of  Imoj-ing  the  metallic  particles  to  the  surface  of  the  Vu\md 
pulp.  In  practice  the  'modification'  of  the  water  is  effected  by  enudsi- 
fication  or  minute  subdivision  (as  in  a  mayonnaise)  of  an  insoluble 
oil,  such  as  cotton-seed  and  oleic;  or  it  may  be  done  by  means  of  a 
soluble  oil  or  derivative,  sueh  as  eresol  and  amyl  acetate. 

Tiie  presence  of  a  contaminant  in  water  may  also  affect  its  vis- 
cosity or  internal  friction,  whereby  it  offers  resistance  to  a  change  of 
shape.  This  strengthens  the  film  of  a  bubble  generated  in  sueh  water. 
Moreover,  it  has  been  asserted'  that  a  concentration  of  the  contami- 
nant occurs  in  the  surface  of  a  liquid,  causing  the  viscosity  to  be  highly 
magnified  as  compared  with  the  body  of  the  liquid,  it  is  also  known 
that  the  films  made  of  any  definite  liquid  are  of  the  .same  strength, 
irrespective  of  their  thinness;  so  that  tlie  atteiniation  of  the  skin  of 
a  bublile  does  not  decrease  its  strength.  This  again  follows  from  one 
of  the  most  remarkable  properties  of  a  bubble:  the  ability,  within 
small  limits,  of  adjusting  its  tension  to  the  load."  Briefly,  the  tension 
at  the  surface  of  a  contaminated  liquid  is  able  to  adjust  itself  within 
fairly  wide  limits.  Thus  a  film  of  such  a  liquid  can  remain  in  equili- 
brium when  a  film  of  pure  liiinid'"  would  have  to  break. 


"Samuel  S.  Sadtler  in  Minf  rals  Separation  v.  Miami  case,  191.5. 

o'Thermod.vnaniics.'  by  Willard  C.iblis.  PaRe  Sl^.  "In  a  thiclv  film,  the 
Increase  of  tension  with  the  extension,  which  is  necessary  for  its  stability 
with  respect  to  extension,  iy  connected  with  an  excess  of  soap  (or  some  one 


r\f    ita    fnntrmnaTtia'i     nf     thj> 


I'^In  a  chemically  pure  liquid  it  is  imiKJssible  to  form  froth  or  multiple 
bubbiinff.  Some  difTerentiation  of  the  components  of  a  liquid  is  required  to 
make  a  film. 


14 


TIIK    FLOTATION    I'KOCKSS 


111  liis  liddk  'I'.  -1.  IIimivit"  stiiti's  hdW  tlic  prrM'iiic  of  <i  iiicrc  trare 
of  siipoiiiiK'  will  kill  till'  t'rotli  in  the  Hotatioii  icll.  lie  docs  not  explain 
why.  It  liap|)eMS  tli.it  sapoiiine,  wliieh  can  lie  ilistiolved  out  of  horse- 
chestnuts,  is  ail  aiil  to  the  lilo'vin;;  of  lii<;  Imhliles.  Hut  they  are  weak 
iuiil  teiiiler.  Why?  Heeause  sapoiiine  iitin  dsi  s  Ww  tension.'-  When 
a  saponine  liulilile  is  lirouLrht  into  contact  with  a  s<iap  liublile.  the 
foriiu'i-  contracts  and  Mows  air  into  the  soaji  hiiMile.  l{ayleit;li  prove! 
that  the  tension  of  the  .soap-liliii  is  only  two-thirds  of  that  hlown 
from  ii  sajxmine  solution  of  ecpial  stretifitli.  One  part  of  sa|ioMiiie  in 
lOO.Ono  parts  of  water  will  siitlice  to  make  a  lilieral  froth.  Hut  the 
hulttiles  are  flimsy.  They  are  so  frafrilc  as  to  render  them  of  no  use 
as  (iirrici-s  of  mineral.  Hence  they  sjioil  the  normal  working  of  a 
flotation-cell,  in  which  it.  is  neces.sary  to  employ  a  contaminant  that 
lowers  the  surface  tension  so  as  to  yield  liuhhles  that  are  both  per- 
sistent and  sutlicieiitly  rolnist  to  huoy  mineral  particles. 

Ill  approachinfj  the  rationale  of  the  }ii'ocess  under  discussion  it 
may  now  he  as.sumed  that  we  are  dealinir  with  a  pulp  consistiiifr  of  ore 
and  water,  modified  hy  oil,  the  ore  having  lieen  crusht>d  sutlicicntly  to 
s-parale  the  metallic  sulphides  from  the  a.ssociated  fjrnnfrue  in  a  pulji 
consisting  of  minute  particles  of  each.  In  ordinary  water-conetMitra- 
tion  the  lower  specific  gravity  of  the  gaiigue  jiermits  the  mill-man 
to  wasli  it  away  from  the  heavier  metallic  sulphides,  hut  in  the  flota- 
tion jiroccss  this  action  is  reversed,  the  iiictalli<'  particles  hcing  lifted 
ahove,  and  away  from,  the  f,aiigue  particles.  Apparently,  it  is  a 
metallurgic  anomaly.'^ 

To  this  crashed  ore  we  have  added  oil.  The  oil  serves  as  a  con- 
taminant that  lowers  the  surface  tension:  als<'  it  augments  the  vis- 
cosity of  the  liquid.  These  two  effects  unite  in  facilitating  the  forma- 
tion of  strong  and  persistent  huhhies.  The  necessary  air  is  introduceii 
hv  agitation  or  h.v  direct  injection.  Kea-weed  contaminates  sea-water 
and  makes  foam  in  the  lireakei's.  as  oil  makes  froth  in  fresh  water 
that  is  agitated. 

Air  hius  a  marked  adhesiveness  for  metallic  surfaces:  this  attach- 
ment is  supposed  to  he  enhanced  hy  the  presence  of  oil  or  grease  on 
the  metallic  surface.  In  other  words,  the  metallic  surface,  such  a.s 
that  of  a  sulphide  mineral,  when  in  the  presence  of  both  oil  and  water, 
will  exhibit  a  preference  for  the  oil.     Ilciice  the  sulphide  is  not  wetted. 


u'C'oncentratinc  Ores  liy   Flotation.'     Pape  99,   Second   Edition, 
i='Soai.  nubbles.'     By  ('.  V.  Roys.     Page  115. 

'■'Mr.   Ingalls  bas  called   it   'loncentration   upside  down;'   Mr.   Norris  has 
called  it  a  'paradox.' 


THE    KI.OTATION    I'KOCESS 


15 


Tins  clianictiTistic  is  less  marked  on  the  ])art  of  tlic  heavy  silicates, 
swell  as  rhodonite  or  parnet.  and  still  less  evident  in  the  ease  of  the 
lighter  silieious  minerals,  sueh  ils  ([iiartz  and  orthoelase.'*  The  addi- 
tion of  acid  lessens  the  oil  atlaehinent  to  the  fiiingne  particles  without 
decreasing  the  seleetiveness  of  the  oil  and  the  air  for  the  sulphide 
particles.  Thus  we  can  undersUind  why  the  huhliles  attach  tlienis«dves 
to  the  metallic  parti(des  and  liuoy  them  to  the  top,  while  ignoring  the 
ganguc  particles,  which  sink  to  the  bottom  of  the  vessel  in  which  the 
pulp  is  undergoing  stirring  or  agitation.  This  preference  of  air  for 
metals  and  metallic  surfaces  must  he  emphasized.  It  is  the  decisive 
factor  in  the  process  of  flotation.  Most  minerals  when  pulverized,  and 
then  sprinkled  on  water,  will  float,  particularly  if  they  are  in  flakes 
or  plates,  as  gold  often  is  and  as  minerals  with  a  highly  developed 
cleavage  usually  are.  Sueh  flotation  is  due  to  air.  which  forms  a  dis- 
contiiuious  fllm  under  the  mineral  particles.  Mickle  proved  this  by 
taking  a  magnetic  mineral,  like  pyrrholite,  and  pulling  it  out  of  the 
water  by  a  infignet,  when  it  could  be  seen  that  the  w  iter  was  dragged 
up  with  the  mineral.  These  minerals  float  for  the  same  reason  as  an 
ungreased  needle  will  float,  namely,  the  resistance  to  rupture  of  the 
surface  of  the  water  and  the  aid  of  the  air  attached.  It  used  to  be 
supposed  that  the  needle  must  be  grea.sed  in  order  that  it  may  float. 
That  idea,  like  the  general  exiiggeration  of  oil  as  a  factor  in  flotation, 
has  b(>en  disproved  In-  experiment.* 

If.  to  water  in  which  mineral  dust  is  floating,  an  addition  of  alcohol 
or  caustic  soda  be  made,  or  even  the  vapor  of  alcohol  be  allowed  to  play 
on  the  surface  of  the  water,  the  mineral  particles  will  sink.'"'  The  con- 
tamination of  the  water  has  decreased  its  .surface  tension. 

The  bubbles  collect  the  metallic  particles,  that  is  agreed:  but 
whether  the  selection  is  dependent  upon  the  previous  oiling  is  a  dis- 
puted point.  Apparently  the  adb.esiveness  of  air  for  metallic  surfaces 
is  greater  than  that  of  oil.  and  it  would  appear  probable  that  in  the 
flotation  process  the  first  phenomenon  suffices  without  the  aid  of  the 
second.  It  used  to  be  an  accepted  canon  of  flotation  thnt  the  oil 
coated  the  metallic  particles,  which  therefore  were  not  'wetted'  and 
did  not  sir.k.  while  the  gangue  particles  were  not  oiled  and  therefore 
were  wetted,  espcci  j.iy  in  acidulated  water,  so  that  they  sank.  Testi- 
mony has  been  given  by  a  keen  observer  that  "the  distribution  of  the 


"■'Tienriitir  A.  iMiikie.     i-ioceeiiinKs  oi"  the  Koyal  bocletv  of  Victoria.    Vol 
XXIV,  part  2,  1911. 

*Spe  pages  327  and  356  of  this  bool<. 
i-/&iVf 


IG 


■rUF,    FLOTATION    I'ltOCESS 


Oil  ill  tilt'  <'()ii('fiitriili;  ami  tlir  Kaii'^iU'  is  rntiniy  tortiiitous. "'  '  It  is 
uveii  a'»erted  now  that  instead  of  the  oil  nsidiiij,'  with  tln'  niriailir 
liartii'lts  cxc-liisivciy.  and  leavinn  llic  ^raii^ciu'  i.iiloiU'iird,  it  is  dis- 
triliutrd  tliroii^liiiiil  the  iiiixtun'.  When  the  larger  proporlioiis  of  oil 
were  cinployt'd.  it  is  likely  that  siuii  proiiiisciious  oiliiii?  of  all  tin' 
[(articles  of  the  juilp  did  take  plaee.  hut  now  that  the  ipiaiitity  has 
heeu  ri'(luced  to  a  jn-oportion  so  small  that  the  jireseiiee  of  oil  on  the 
eoneentrate  is  not  diseernihle  hy  the  senses,  we  may  assume  a  pii'i'.T- 
eiiee  for  the  metallic  particles  in  accordance  with  lahoratory  ohsrrva 
tion.  Tiiis  appear.;  to  he  contirmed  hy  i-xperiments  showini;  that  in 
the  case  of  speeilie  minerals,  such  a.s  chalcocite.  it  is  nccfs.sary  to  oil 
the  mineral  in  order  to  lift  it  hy  an  air  Inihhle.'' 

Wlii'ii  usinc;  the,  at  i)iesent,  minimum  ciuantity  of  oil — say.  one- 
third  of  a  pound  per  ton  of  ore — it  would  a])i)ear  that  the  oil  forms  a 
coatinjr  of  microscopic  thinness  upon  the  metallic  pai'licles.  The 
minimum  thickness  is  the  thi<'kness  of  a  molecule.''' 

Metallic  surfaces  have  a  selective  adhesion  for  air  and  for  oil.  as 
we  have  seen.  Therefore  the  molecular  forci's  of  the  oil  and  of  the 
metallic  surface  may  he  sujjposcd  to  unite  in  attractiiifj  the  hultliles. 
What  the  nature  of  those  forces  may  he  is  yet  a  matter  of  I'onjecture. 
althoufrh  the  idea  tiiat  they  arc  electro-static  is  su-iiiested  hy  the  fa.'t. 
amoiif;  others,  that  the  metallic  sulphides  most  amenahle  to  flotation. 
are  pood  eonduetors  of  eh>ctrieity.'" 

The  forefroiner  statement  of  physical  principles  applii'S  more  par- 
ticularly to  the  frothiiift  method.  The  history  of  the  'prior  art.'  as  it 
is  called  in  patent  litifration,  shows  that  the  first  stap:e  of  the  flotation 
l)roeess  as  now  in  vopne  was  performed  hy  the  use  of  a  large  propor- 
tion of  thiek  oil.  This  is  typified  hy  the  hulk-oil  method  of  the 
P^lmore  hrothers.  It  depends  upon  the  lower  specific  jrravity  of  oil 
as  compared  with  water,  so  that  when  mixed  in  a  pulp  of  ernslied  ore 
the  oil  rises  to  the  top.  dragprinfr  the  metallic  sulphides  with  it.  This 
also  was  explained  formerly  as  due  mainly  to  the  selective  adhesive- 


I'lBertram  mount.  teatifyiiiK  for  Minerals  Separation  in  the  Klniore  appeal 
before  the  Privy  Council.  I  niiRht  aild  that  fortuitous'  is  a  word  that 
describes  other  things  in  the  historv  of  notation  besides  the  oiling. 

iTExperiments  of  B.  H.  Dosenbach  in  the  Minerals  Separation  v.  Miami 
suit,  at  Wilmington,  1915. 

is'Oil  Films  on  Water  and  on  Mercury.'  iiy  Henri  Devaux.  Mininij  and 
Scientific  Press.  .Tuly  31.  I'.uri.  page  l&K. 

H'The  Electrical  Theory  of  Flotation.'  By  Thomas  M.  Bains,  Jr.  Mininfj 
ami  .^eicniiflc  Press.  November  L'7  and  December  11,  1915.  See  also  page  225 
of  this  book. 


Tin;    ri.nT\TI()\    lH(i(t> 


i: 


ncs-s  lit'  nil  \'<iv  nirtiillii'  siift'ac-cs,  wliidi  prcvfiils  tliciii  lioiii  luinf; 
wt'ttcd,  while  the  luck  oi'  a  siiiiiliir  affinity  on  the  part  of  lln'  ^Mrifrin' 
particles  eiiaMes  them  t(i  lir  so  wetted  as  to  cause  them  to  sink  to  the 
hottoiii.  All  oi'  tins  is  incasuralily  true,  hut  the  utiderlyiii','  fact 
seems  to  he  that  an  excess  of  viscous  oil  causes  thi'  oil.d  partiilcs  to 
adhere  or  sti'k  toffether  so  that  tliey  are  rat'ti  d  to  tiic  top.  It  is 
prohal)Ie  that  when  thus  ccilhctid  in  jrroups  they  are  more  readily 
floated  on  account  of  tlieir  ahility  to  iiold  more  oil.  as  compared  with 
individual  jiarticlcs,  hccause  the  oil  tills  the  spaces  hetwecn  the 
memhers  of  a  group. 

The  lighter  oils  have  a  specitie  gravity  ranging  from  <).S  to  0.!  ;, 
as  compared  with  the  1.(1  of  water,  so  that  tiie  margin  for  flotation  is 
small.  For  instance,  in  the  case  of  a  mixture  of  an  oil  havinu'  a  specitie 
gi'avit.v  of  (l.il  and  of  zinchlende,  ha\ing  a  s|)ecific  gravity  of  4.  it  is 
necessary  to  use  (J. 7  parts  hy  wciglit  of  oil  to  ont^  part  tiy  weight  of 
hleude  in  order  that  the  mixture  may  have  a  specific  gravity  e(|ual  to 
that  of  water.  Thus  an  ore  containing  20%  blende,  or  400  Ih.  j)er 
ton,  woidd  re(iuire  the  use  of  over  2fi80  II).  of  oil  in  cn'der  to  float  all  the 
hlende  in  the  ore. 

In  true  hulk-oil  flotation,  which,  as  a  matter  of  fact,  was  rarely 
performed,  the  phenomenon  of  surface  tension  does  not  play  a  promi- 
!ient  part.  It  is  mainly  a  fpiestion  of  raising  a  mineral  heavier  than 
water  hy  aid  (d'  a  licpiid  litrliter  than,  and  "ot  soluble  in,  water.  The 
emidsification  of  the  oil  was  carefully  a\  ided  by  Elmore.  In  the 
later  phases  of  flotation,  in  which  the  proportion  of  oil  becomes 
steadily  less,  it  is  aimed  to  emulsify  the  oil  and  air.  The  oil  prodiices 
a  'uncro-emulsion  of  air,'  as  Leverrier  expres.sed  it.  Thus  the  air  is 
tlioroughly  distvihuti.d  in  the  pulp  and  the  oil  is  brought  into  intimate 
mixt're  with  the  water,  which  is  thereby  modified  and  prepared  for 
the  making  of  persistent  bubbles. 

Tin:  Pkocksses,  The  application  of  tlie  various  physical  princi- 
ples outlined  in  the  foregoing  paragraphs  has  taken  diverse  forms,  as 
expressed  in  scores  of  inventions,  only  a  few  of  whieh  have  been  de- 
veloped into  workable  processes.  The  phenomenon  of  surface  tension 
is  used  direetl.v  in  the  s(>-ealled  skin-flotation  methods  of  Hezekiah 
Bradford.  Arthur  P.  8.  ^laeqnisten,  and  Henry  E.  Wood.  In  the 
first  of  these,  invented  in  1886.  the  pulp  flows  down  an  inclined  plane 

OTitn  flip  nnipt   smrfnpp  nf  irofpr  in    a   vpccol     or»  tViat    +li(i 


1  lr^V»iHn 
••1 


par- 


ticles float  forward  under  the  impetus  of  their  descent  while  the 
gangue  particles  sink.  See  Fig.  2.  The  explanation  is  that  sulphides, 
by  exposure  to  the  atmosphere,  attach  films  of  air  to  themselves,  so 


18 


TilK    FLOTATION    l'KO0E88 


tlial  they  iiri'  ikiI,  wdli-il  and  iiiovc  ovtr  tin'  wicallfd  uattT  skin,  uliili- 
the  gariK'i'',  which  hfis  roiiiained  wet  tlirnuuhciiil  tiic  (ipiTaticiii.  sinks 
throui^h  Ihi'  surrai'i'  to  tlie  hottoni  of  the  vessel. 

.Mai(|iiisten  applied  the  siiiiie   idea  in  a  tiilie  ea.st   witii   a   helii'al 
j;roove  and  revolved  at  a  moderate  sjired.      In   l!i(l(i  this  method  was 


(ho  MiJM.I 


2  atieen  — Slisel   1 


H.  BRADFORD. 

METHOD  OF  SAVING  FLOATINO  MATLRHLS  IN  ORE  SEPARATION. 

No  345,951.  Patented  July  20,  1886. 


^Jnt-tnJit. 


Fig.  2.     tiik  bK.M)roiii)  i'.\tknt. 


TIIK    l-l,i>T\T|nN    I'FfiiCKSS 


1!) 


ailiipicd  ill  llic  Adi'liiidc  iiiili.  al  (ioliniiilii,  X  vjula.  'I'lic  ore  roii- 
taincd  2.29(  '^oppcr  as  I'liah'npyiitc,  with  pyrrlidlitc  and  pyrili-,  as 
well  as  sdiiic  lilciidc  and  tfali-iia.  Tlif  naii(;in'  was  <|iiart/i)S(',  (•(iiitain- 
in^^  si)in('l  and  (Lrariicf.  'I'lic  tuhcs  wen'  id'  cast  in  in.  (i  ft.  Il)n^^,  1  I't. 
iiisidi'  dianit'ttT,  and  cacli  wci)»hfd  4r»()  lli.     Sii'  Fijr.  ■!.     KxtcriiHlly 


Flo.   3.      TIIK   MAI  yriSTEN    TIBK. 


these  tubes  were  cfst  with  two  tires,  whieh  rested  upon  supporting 
rollers.  The  diseharge-end  was  entirely  open.  The  feed-end  was 
closed  except  for  a  hole  in  the  eetitre  large  enough  to  admit  the  pipe 
through  whieh  the  pulp  entered.  Inter-  ally  the  tube  was  cast  with  a 
helical  groove  of  :]-inch  pitch,  which  was  changed  suhst>quently  to 
li-inch  pitch.  The  discharge-end  was  connected  with  a  separating- 
box,  the  joint  between  tliis  and  the  tube  lieing  water-tight,  while  the 
tube  was  free  to  revolve.  At  the  side  of  the  separating-box,  directly 
opposite  the  discharge  from  the  tube,  an  opening  or  lip  was  cut  for 
the  overflow  of  the  surface  layer  of  water,  carrying  the  floating 
nuneral.  This  opening  regulated  the  depth  of  water  in  the  tube.  The 
bottom  of  the  opening  was  three  inches  above  the  inside  bottom  of  the 


20 


Tin:    FLOTATION    I'ROCEPS 


tube,  so  that  IIkto  was  llu'fc  iiiclics  (if  water  in  tlic  tiilic:  tln'  tVcd  ami 
the  diseiiarpe  wen'  s(i  refrulated  that  the  water  pa.ssiiiji  over  tlie  lip 
was  about  ,;',  iiieii  deej).  The  tube  was  rotated  at  -lO  r.p.ni.  in 
a  direetidii  corfespoiidinf.'  with  the  iielix  ot'  the  iiiti-rior.  As  Mr. 
Ttijralls  said:''  "The  l)ul|>  is  thus  sen'wed  tliroujxh  the  tulie  and 
in  its  advauee  is  rejieatediy  jjriveii  an  ('i)i>(irtunity  ti>  slide  u])on  the 
sui't'aee  of  the  water,  where  it  may  be  I'etained  by  surfai'<'  tension." 
The  ore  was  e>-u.'^lie<i  to  pass  ;!0  iiiesii.  The  eaiiacity  of  each  tube  was 
o  tdus  ]")er  "24  hours,  and  2.")  tubes  were  in  use.  A  eoneentratimi  of 
11:1  was  I'tVected  (HI  a  2:2'',  eopper  (ire.  tl'e  tailing  ass.iyiuET  ^12%; 
but  this  refers  only  to  the  de.slinied  ore.  tiiat  is  70';  of  tlie  siip]>iy,  so 
that  tile  actual  extraction  was  only  (>:!'",'.  Tlie  inability  to  treat  sliii  e 
is  a  notable  det'ect  of  this  itip;eni(ni.s  method  (if  flotatidn. 

AVood's  methoil  is  e(|ually  interesting.  The  ore  is  ernslK d  dry 
to  :iO  or  40  mesh  and  is  then  fed  in  a  thin  strmim  from  a  vibratiiia; 
plate  onto  the  surface  of  water  in  a  Ian''  to  the  surfaee  of  which  a 
forward  movement  is  given  by  small  jets,  also  of  water.  By  a  eom- 
binalidii  (if  the  capillary  attraction  and  the  pressure  of  a  ediistant 
feed,  the  sidiihides  are  caused  to  move  forward  as  a  detinile  elastic 
film  on  top  of  the  water.  This  film  of  mineral  jiasses  over  an  endless 
canvas  belt,  which  emerges  from  the  tank  at  a  particular  angle,  varied 
aceordiug  to  the  kind  of  minei'ai  to  be  saved.  The  belt  with  its  tilin 
of  sniphidis  passes  over  three  rollers  sii  that  its  motion  is  revei-sed 
when  it  strikes  the  water-level  of  a  second  tank,  where  it  I'elcases  its 
vahialle  burden.''  Very  little  gangue  in  siisjiension  eomes  over,  as 
the  water  drains  'laek  into  the  main  tank.  Any  submerged  pjirticles 
that  have  been  ai  cidentally  wetted  or  are  so  heavy  that  they  have 
]ieneti-ated  the  surface-film,  pass  to  standard  ciuicentration-taliles.  on 
which  they  are  separated  by  gravity  in  the  (irdiuary  way.  In  the 
case  of  nidiyhdenite  and  gi'aphite.  the  til^i  cdMcentrate  is  still  further 
cleaned  by  lieing  passed  (iv(>r  a  neai'ly  vertical  screen,  (iangue  in  sus- 
pension passes  tlnough.  while  the  flat  crystals  of  tlie  valuahli>  minerals 
slide  over  the  sc"een.  whicM  largely  dewaters  them.  The  flotation  con- 
centrate is  collecteii  and  (lrie(l  as  usual.     See  Kitr.  4. 

Mr  Wood  is  using  his  own  jiroeess  to  eonuiiercial  advantage  in 
the  treatment  (if  molvhdenite  ore.  at  Denver.     The  ^rac(!uislen  tube  is 


■'"The  whole  of  the  aliove  description  is  taken  from  the  adniiratile  technical 
article  liy  W.  I\.  Ingalls  in  T'oncentration  t'pside  Hown.'     F.iifj.  <(  Mill.  Jour., 

■ 'P'rom   iiarticiiliiis  siivcn  to  ni!>  liy  Mr,   Wood  himself.     See  also  Trans. 

A.  I.  .M.  E..  Vol.  xi.iv  (itui;),  pp.  i;s4-;iii. 


TriE    FI.dTATION    I'UOCESS 


21 


still  ill  usr  at  .Miilliiii.  Idalio;  Imt  tlic  Uracilnnl  pati'iit  is  only  of 
afail'iiiic  interest.  Tiicst'  iiietiinds  liavc  liecii  coiit'iist'd  with  the  more 
recent  flotation  processes:  tliey  oupflit  to  lie  (litlf'erentiatril.  I  siif?gpst 
therefore  that  tiny  he  classed  under  'filin-siispension,'  for  it  may  lie 


i 


Fici.    4.       IIIK    WOOD    MAllIINK. 


taken  that  in  every  case  the  sulphides  arc  cai'ricd  with  air  over  the 
tcnsional  tiliii  on  the  surface  of  the  water. 

Incidentally,  it  may  he  well  to  point  out  that  altlioii<;h  it  is  con- 
venient to  speak  of  the  'water-skin'  and  of  skin-flotation,'  the  u.se  of 
cither  'skin'  or  'tilin'  is  inaccurate.  .A  skin  is  a  thing  of  ili'tiiiite 
thickness,  which  therefore  can  be  'peeled'  off.  like  the  epidermis,  for 


22 


Tin:    I-l.i)TATION    rUMCESS 


exainplf.  'I'lic  iihi'iinineiini;  of  surt'iiri'  tension  iiivolvfs  nothing  of 
tho  kind.  It  n fcrs  to  a  comlilion  of  molcc-ulfir  fori'es  at  the  surface 
of  a  liquii!.  till'  ctVfrt  <il'  wliirji  ran  iir  only  one  niolecuh'  tliicl<.     Tims, 


No.  776,145. 


PATENTED  NOV.  29,  1904, 


C.  V.  POTTER. 
PROCESS  OF  SEPARATING  METALS  FROM  SULFID  ORES. 


APPtlCATIOI  rjLED  Jil. H. 1902 


.^^ 


Flo.  3.     iiiE  I'OTTLH  1'.\ii:m-. 


TIIF.   FLUTATIOX    PROCESS 


2:3 


'watiT  skin'  and  'skin-flotation'  stand  for  watcr-surfat-e  and  siirface- 
Mispeiision. 

Neither  Bradford  .  r  Wood  nsis  oil  or  acid,  but  in  tlie  later  ap- 
plications of  the  .Mae(|wisten  tiilie  hoth  have  been  intnxhieed.  As  the 
ore  contains  carbonates  that  would  react  with  the  sulphuric  acid  so 
as  to  liberate  eartjon-dioxidc  f;as.  it  is  obvious  that  another  factor  is 
introduced,  namely,  the  bubble  idea,  which  has  proved  so  potent  in 
tlie  itiore  recent  phase  of  flotation.  The  further  addition  of  oil  marks 
a  distinct  departure  from  the  first  idea  of  tlic  inventor,  causinjj  the 
process  to  resembk-  those  of  Potter,  Delj)rat,  and  De  Bavay. 

The  methods  of  these  three  Australians  were  alike  desigrned  to 
treat  Broken  Hill  tailinps.  containinfr  zine-lead  .sulphides  in  a  gangue 
composed  partly  of  carbonates,  notably  calcite,  sid.^rite,  and  rliodo- 
chrosite.  Charles  V.  Potter  used  water  containing  from  1  to  10% 
sulphuric  acid,  wb.ieh  was  added  to  crushed  ore  placed  in  a  vessel 
I  see  Fi<r.  o!  provided  with  stirrers  [  li'  the  shaft  and  H  the  arms.) 
Heat  was  then  applied  by  pas  (li)  ;  whereupon  the  metallic  particles 
rose  to  the  surface  of  the  liquid.  It  has  been  said  tliat  "it  is  clear 
that  he  (Potter)  had  in  view  a  surface  tension  proces.s."''  if  this  is 
mi'ant  as  a  reference  to  the  surface-stispension  method,  .say,  of  Brad- 
ford, it  is  incorrect.  Suivly  Potter  used  bubt)le-lcvitation  as  his  prin- 
cipal etTeet.  The  gas  generate<l  by  the  action  of  the  acidulated  water  on 
the  carbonates  joined  with  the  air  entrained  liy  tjic  ore  is  furnishing 
gas  for  making  bubbles,  this  result  being  assisted  further  by  the 
stirring  of  the  pulp  and  the  heating  of  it.     See  also  Fig.  10. 

(i.  D  Delprat  had  an  apparatus  suggesting  the  employment  of  sur- 
face suspension,  but  he  also  used  chemicals  to  induce  flotation.  See 
Fig,  6.  By  the  addition  (through  the  jiipi.  f))  of  a  hot  solution  of 
acid  salt-cake  to  the  eru.shed  ore  as  it  was  fed  (from  the  chute  1) 
upon  a  pan  having  a  sloping  liottom  (4)  heated  by  a  Bunsen  burner 
(14).  the  sulphides  were  made  to  rise  to  the  surface  of  the  vessel 
(at  '.i.  pas,sing  forward  ahmg  l.T).  while  the  gangue  collected  in  a 
sump  (10).  In  this  ca.se  also  the  flotation  was  the  restdt  of  forming 
bubbles  of  carl)on-dioxide  gas  and  of  air  by  chemical  action  and  heat. 
Auguste  J,  F,  de  Bavay  described  a  jiroccss  in  which  a  (bin  stream 
of  freely  flowing  pulp  was  delivered  uj.on  the  surfiu-e  of  a  ves.sel  of 
water,  after  (he  style  of  Bradford.  The  description  of  the  metliod  as 
used  sulKsequently  on  the  North  Broken  Hill  mine  docs  not  correspond 
with  this,  for  in  that  plant  the  mill-tniliriLr   relieve,!  nf  slime,  is  9a\<V 


a.vConcpntrritini];  Ores  b.v  Flotation. 
■Mlhiil.     I'iiKt'  115. 


Paire  0. 


24 


Till-;  ri.nr.\Tiii\   n!nci>^ 


to  li;i\i'  1h'i-ii  I'c.l  into  H  XTssi'l  pr'ovidcd  \\illi  ;i  luixiiii;  drvicc.  I'Uii  iit 
it  liiu'll  speed,  so  iis  to  ii>ritate  the  ;ieidul;ili-d  puljt.  The  sulphiih'S  I'ose 
to  tlie  surtViee.  nnieh  in  tlie  siiiiie  Wiiy  as  in  tiie  |)reeediii^  methods  of 
Potter  and  Delpi'at.  Tiiat  of  I'otter  was  useii,  in  a  moditicd  form,  at 
the  Hloek  II  mine  at  Hi'oi<en  Hill  in  IHn:,  ;ind  llHKi,  while  the  Delprat 


Nv.  763, S62  PATENTED  JDNE  :8,  1904. 

":.  D.  DELPHAT. 

APPARATUS  FOR  DSE  IN  CERTAIN  PROCESSES  OF  EXTRACTING  SPLFIDS 

FROM  ORES. 

AfPLIOiTIOf  riLCD  HAI    a,  t»03 
RO  HODEL 


te^: 


yy.:- 


N*^T2-**^fc*vUH/*'' 


1 


3  .y%i"Vrt 


Fa..  \'>.     1  III    iii.i.i  liM'  r\Ti     r. 


THE    i-LOTATION    PROCESS 


luucess  has  heuii  in  use  lor  sevcnil  years  siULvs-snilly  at  tlie  Bmk.'ii 
llill  l'rn|,rirtar\  mii.  .  It  is  prup.-r  t„  a.i,l,  iK.uvvi'r.'tliat  all  of  tlifsc 
aciii-riotatioii  iiiptliods  aro  now  only  of  academie  interest.  In  the  ciiiet 
applieation  of  these  j)roi-esses  it  has  not  heen  eiistoinary  to  use  oil, 
but  as  the  material  treated  came  from  old  dumps  of  tailins?  it  may  he 
assum.'d  that  th.'re  was  some  sulistan.-e  present  .■ai)al)le  of  modifyin-r 
tile  water  sufficiently.  ■" 

The  first  aj)i)lieation  of  any  of  the  oil-tlotation  proee.s.s(^s  on  a 
workin<r  .seah'  in  a  mill  was  that  made  at  tiie  (Ha.sdir  mine,  near 
l>i>l':elly.  in  Wales,  hy  Francis  E.  Elmore  in  18!i!l.  Tlie  mi.xture  of 
erushed  ore  and  wafer  was  fed^^  at  the  up|)..r  end  of  a  .slowly  revolv- 
ing drum.  i)rovide.|  with  anindar  helical  ribs  aiul  transvers."  blades,  .so 
as  to  etTect  the  mixing'  of  the  pulp  and  the  oil  without  i)rodueinj? 
emulsification.  See  Fig.  7.  The  oil  wa.s  introduced  fhrou5,'h  a  sep"- 
arale  jjijic.  The  mixture  was  discharfred  info  a  V-shaped  vessel,  where 
the  water  and  sand  subsided  wliih.  the  oil  huoycd  the  .sulphides  to 
the  top.  An  oil  residuum  liaviufr  a  speeific  gravity  of  0.89  wa.s  used 
in  e(inal  parts  hy  weifrht  with  the  ore.  ton  for  ton.  The  oil  was  so 
viscous  as  to  rc(iuire  the  aid  of  small  rotary  pumps  to  propel  it  for- 
ward^ The  temperature  of  the  oil  and  water  was  kept  between  54° 
aiul  r)7-F.  The  loss  of  oil  was  2  gallons  per  ton  of  ore.  A  concen- 
tration of  14: 1  was  achieved  with  a  recovery  (in  the  concentrate)  of 
6f>^;  of  the  gold,  G5%  of  the  silver,  and  70%  of  the  copper  from  a 
I>yritic  and  chalcopyritie  ore  as.saying  1.12%  copper,  0.04!)  oz.  gold, 
and  0.8  oz.  silver  per  long  ton.  The  process  was  described  as  "a 
somewhat  dirty  and  nasty  process."  It  did  not  work  on  oxidized  or 
<    I'thy  ores,  nor  upon  tarnishi'd  sulphides. 

In  the  course  of  the  discussion  following  the  reading  of  the  paper 
by  Mr.  Rolker  from  which  these  fact.s  are  gleaned,  it  was  acknowl- 
edged that  the  process  develope.l  by  Mr  Elmore  was  ba.sed  on  pre- 
vious experimental  work  done,  at  tlie  same  mine,  by  George  Robson, 
who  used  petroleum  in  even  larger  proportion,  a.s  much— T  have  been 
informed-  ;is  three  tons  of  oil  to  one  of  ore.  But  the  most  interesting 
fact  elicited  by  the  discussion  was  the  statement  made  hy  ^Ir.  Elmore, 
and  confirmed  by  the  .superintendent  of  the  mill.  John  Bevan.  that  the 

••'■This  suKRcstion   is  ni.ele  liy  Mr    Hoovpr  in  his  l)ool<.     On   pape  101   hp 

says  that    "there   may    I;,,   orwnic   substances   in    the   ore   which,    upon    the 

addition   of   acid,    yield   gummy   compounds   that    seiertivcly   adhere   to   the 

12;.     •„•:;■    ::;:;■  :;;■   ;;r;::;r>:,iy  riioarm  ■oiiipiiuies,'   liiiii    is.  ihe   plenflp  and 

Kalena. 

■"Charles  M.  Rol]<pr.  'Notps  on  thp  Elmore  Toncpnl  ration  Process.' 
Trans.  Ins*    M.  &  y]..  Vol.  VIII  (1S99-lflOO)  pp.  379-3S4 


TIIK    FI.OTVTIitN    rUDLKSS 


actual  loiul  (if  iiiiiicral  rarrivd  hy  tlie  nil  was  2i)'/i ,  as  at^aiiist  tlii' 
theorptical  load  of  10%  inferred  l).v  Mr.  Kolkor.  In  short,  the  oil  did 
150%  more  than  anyliody  eotild  exjilain.  The  'i)rior  art'  was  in  the 
dark,  but  the  p'Sthuiiious  art  of  today  i.ni  make  a  confident  jiuess. 


No   67e.679  Pitented  iunt  18,  1901. 

F    E    ELMORE 
PROCESS  OF  SEP*R«TINC  METALIIC  FROM  ROCKV  CONSTITUENTS  OF  ORES 


No  Mode) 


2  ShMtl-ShtAl    t 


'^■s^. 'ij  ^\ 


Fig.  7.    Tat  eimoui;  paiknt. 


THE    FLOTATION    I'KHCESS 


01'  course,  the  larg.T  part  of  tlie  levitatioii  was  done  l)y  air,  eiitangled 
previously  in  the  ore  particles  and  entrained  suhsecjuently  during 
the  mixing  of  the  pulp  witli  the  oil  in  the  drum.  Later  investigators 
can  testify  how  diflicull  it  is  to  prevent  the  indrawing  of  air  under 
stieh  circumstances.  Therefore  even  in  this  beginning  of  flotation  as 
a  practical  process  the  agency  of  air  was  utilized,  although  unwit- 
tingly. Four  years  later  Walter  ^fcDermott,  who  has  hecn  a  con- 
sistent .supporter  of  the  p:iniore  hrothei-s  in  their  flotation  hu.siness, 
acknowledged  that  "the  agitation  with  the  pulp  results  in  liie  oil 
taking  up  a  very  appreciahlc  quantity  of  air."'-' 

This  fact  was  not  recognized  at  first,  liut  in  i:»()4,  six  years  after 
the  first  bulk-oil  patent  of  18!)8,  Francis  K.  Elinor.'  took  out  his  pat- 
ent for  vacuuMi-oil  flotation.  See  Fig.  8.  In  this  he  subjected  tne 
oiled  and  acidulated  pulp  to  a  vacuum,  thereby  rclea.sing  the  air 
dissolved  in  the  water.  The  air  thus  held  in  solution  amounts  to  2.2'; 
by  volume,  at  sea-level  and  60'F.  By  lowering  the  pressure  and  raising 
the  temperature  this  air  is  ndcased,  thereupon  attaching  itself,  m  the 
form  of  bubbles,  to  the  oiled  sulphide  particles,  which  rise  to  the  sur- 
face. For  example,  the  air  in  a  pulp  of  1  ton  of  ore  to  6  of  water 
suffices  to  lift  .360  lb.  of  zinc-lead  sulphides  in  i  Broken  Ilill  on\*" 
In  actual  practice,  however,  the  weight  of  sulpnides  floated  is  con- 
siderably  greater  than  the  theoretical  capacity,  as  ba.sed  on  the 
efficacy  of  the  air  released  from  solution  in  the  water.  Part  of  the 
work  is  done  by  the  gaseous  carbon  dioxide  liberated  by  the  reaction 
between  the  acid  and  the  carbonates,  such  as  calcite.  eitlicr  in  the 
gangue  or  added  in  the  fonn  of  limestone.  Part  of  it  is  entangled  in 
the  ore  particles  and  part  of  it  is  entrained  into  the  pulp  during 
mixing  In  this  process  the  quantity  of  oil  added  to  the  pulp  was 
reduced  to  10  lb.  per  ton  and  finally,  in  some  cases,  to  as  little  as  ;5  lb. 
per  ton  of  ore.  "he  machine  devised  by  Elmore  was  remarkably 
ingenious  and  to  i.  the  success  of  the  process  was  hirgcly  due.  It  wns 
applied  at  many  mines,  notably  the  Snlitclma  copper  mine,  in 
Norway." 

The  Potter-Delprat  and  the  Elmore  vacuum  processes  are  clearly 
based  on  the  activity  of  bubbles  of  carbon  dioxide  or  air,  or  both. 
Next,  mention  must  be  made  of  Alcide  Froment,  who.  although  he 

■■oThe  Concentration  of  Ores  I).v  Oil."    F.  <f  M.  ,/,.  Fetiniarv  14,  1303    page 
202. 

<"T.  J,  Hoover.     'Concentrating  Ores  l)y  Flotation.'     Pase   102. 
••I'Vacuum-Conrentration  at  Sulitclnia.'     Hoim  Holmsen  and  H.  N.  Rees. 
TtiP  Mining  ^fa(]a?in'',  May  1910. 


28 


Till;  ri.iiTA riiiv  puocess 


LlHORC   \ACu,  'JI 
CONCMrFAiC^i 

i 


mxi/ 


F^"^ — rr 


•i  L\V- 


V-:/^ 


''■"  r . 

L. . g)'-3"     -~ 

Fid.  S.     TiiK  srr.iiKi.M  V  ri  vm. 


riii;  ii.nrvridN   iiiii(K> 


L':i 


\v;is  iKil  ihr  iii\i-iitiir  dl'  ;i  Wdi-kiiiLT  |>riici>.s,  iiil  im  liicnl  thr  iilia  (it' 
violent  airitiitioii  for  llir  iiui,mi.sc  of  ])roiliiciiiir  Imlil.lr-,  <<(  ijiis  iMpidly 
from  ii  i)iiln  coiifiiiniiii.'  I"itli  cilcitr  and  ai'id.  Wliilc  \w  looked  to 
i-ai-!;ou  dioxide  ;is  llie  i;as  I'roiii  wliieli  lo  make  Ids  Imlililes.  lie  did  iin- 
douliteilly  I'ntrain  lots  of  air  and  olitained  the  nse  of  it  in  u'eneratinir 

III-     llllMues  lh;i|    Jlllarlleil   lllemselves   lo   lllr  olleil    Jiartleles.       lie  did    not 

'■"•"I'l'ii'  lid  iiMii  h  oil :  only  -'a  thin  lay,  ]■, "  In  Ids  later  insi  lu.-tions  to 
the  Jlincrals  Separation  company.  uIm.-Ii  liomrlit  his  British  patent  in 

lll<i:i.    he    speeilied    thai    the   oil    was    to    he    t'l-om    1    to    :',\' ;     on    lhi.   oi'e. 

The  next  metliod  was  that  invented  h\  \rtlmr  K.  ('attermole,  also 
in  1902.  it  was  to  hny  his  jjatents  that  the  .Minerals  Se[)Mi'ation  com- 
pany was  orfraiii/.ed  in  i:t():{  liy  .John  Mallot.  J,  II.  ('nrle.  \V.  \V. 
Weiistei.  S.  (ire-iory.  II.  L.  Suhiian.  and  II.  I-'.  K.  I'ieanl.  ('atter- 
mole departed  from  the  jtrior  art.  Instead  of  tloatinu  the  sniphides. 
he  sank  them,  while  the  ".rantriie  was  assisted  to  rise  in  an  upwai'd 
eiirreiit  of  water.  He  added  oil  in  the  imi])ortion  of  4  to  (i','  "of 
the  weitjlit  of  metalliferous  nuneral  luesent  in  the  ore."  tou'ether 
with  ■2',  of  soaj).  so  as  to  obtain  an  i;j.'^domenition  of  fl'n-eulent  sul- 
phide particles,  wliieh.  heinjr  heavily  oiled,  stuck  to  I'ach  other,  in 
trroups  or  trranules  that  sank  to  the  bottom.  He  used  a  (lahhett.*  (U- 
eoiie-mixer,  to  obtain  a  violent  airitation  of  the  pulp,  and  foHowed  it 
liy  a  prentler  stirrinir  durin<r  which  the  .separation  into  ''shotty  gran- 
ules" was  effected  in  the  presence  of  as  little  air  as  possible. 

This  proeess  was  only  put  to  work  in  one  mill,  on  the  Central  mine 
at  Uroken  Hill,  where  it  must  have  seemed  a  inetallur<iical  abortion 
during  the  very  short  time  =.t  was  in  use.  The  oil  was  emulsified  with 
soft  soap  and  then  fed  into  the  mixers,  where  the  erushed  ore  under- 
wont  apritation  with  acidulated  water.  From  the  very  start  a  con- 
siderable proportion  of  mineral  was  floated  on  the  froth  incidental  to 
violent  mixing  in  the  presence  of  air.  Apparently  only  a  part  of  the 
sulphides  was  ':  -anulated,'  so  as  to  sink  accordiufr  to  program.  The 
remainder  was  floated  mnntenlionally.  The  description  f;iven  by 
the  manap  .  James  Hebliard,  indicates  that  he  and  his  staff  stumbled 
upon  the  so-called  ajiifation-froth  process  almost  immediately.  lie 
^ecor(^^'-  how  he  discovered  that  more  froth  was  made  by  usintr  less 
oil,  and  that  the  frothing  and  floating  proved  a  better  method  than 
the  graiHilating  and  sinking  of  the  sulphide  particles.  He  also  slates 
that  the  discovery  was  made  concurrently  by  the  metallurgist*^  of 


'-"Flot.ition    at    the    Central    Mine,    Broken    Hit 
Mining  and  .^rirntifir  Press.  Septembei    t,  191.'). 
■"■'•The  actual  operator  was  Arthur  H.  Higsins. 


By    .James    Helihard. 
♦See  Fig.  41. 


30 


THE    FLOTATION    PROCESS 


till'  .Miii.iMls  Si'pinMliiiii  cii.iipany   in   tlif   I, Idn   litlioriiidi-y.     'I'lirv 

liit  iipipii  till'  Niiiiif  idia  hy  varyiii'r  tin-  r|iiaiiii1y  of  oil.  in  .March  l!l(l.'). 
s()  wr  arc  told.  Vet  the  plant  at  the  Central  'nine  was  allnwed  tii  start 
on  tic  Caltenriiile  prneess  ill  .Inly.  SiHTrsshll  tests  with  the  t'nith- 
in;;  pnncss  were  not  made  until  Se|)teMil"  r.  the  pni|)(M-tion  of  nil 
licin^'  rednceil  I'nMn  '■',',  when  ^'rannlatini;  lo  h.'tween  (1.1.")  and  n,2'; 
when  I'rothint;.  The  plant  was  irradually  ehanjied  until  irranulatinn 
was  completely  ousted,  hy  di'iMvasiuj,'  the  ipiaiitity  ol'  oil  and  incrcasiiii: 
the  violence  of  a^'ilation.  The  on'  from  the  mixers  was  passed  with 
"a  jrooil  s|)lash"'  into  spit/kasten.  thci-ehy  aceentuatin^  the  need  for 
aeration. 

So  the  failui-e  of  ilie  Cattcniiole  method  is  stated  to  have  led  to 
the  .Minei'als  Separation  process  of  today,  the  iimprielary  rii.'hts  to 
which  are  lia.sed  prim.irily  on  T.  S.  patent  No.  8:ir>.12(),  date.]  May  2!t. 
IIMI,").     This  is  a   i)roccss  •■wherein,  hy  th(>  u.s»>  of  a   frothing;  afjent, 
and  in  the  pi-eseiiee  of  such  airitatioii  as  will  maintain  or  produce  dis- 
trilnition  of  the  ore  [(articles  tlironixh  the  pulp,  and  dis.spiinnation  of 
liuhhies  of  air  throufrh  the  pulp  and   into  contact   with  the  metallic 
particles   throutrh    the   [(ulj).    the   air   huhhlcs   will    seize   Uie    metallic 
particles  and  will  carry  them  to  and  throuKh  the  surfaoo  of  the  pulj). 
so  as  to  iiermit  of  their  delivery  at  or  al)ove  the  surface  of  the  ]Milp 
.sei)arate  from  the  ^'an^ne  [(articles."     Tills  description  is  taken  from 
the  complainant's  liricf  in  the  suit  of  Minerals  Separation.  Limited. 
r.  Miami  ('op]>er  < 'om])any.  liU.').     It  is  further  explained  that  In  this 
process  "the  frothing  agent  is  an  oil  or  immls<Mt)le  licpiid.  and  the  dis- 
covery was  that  this  mod(>  of  operation  in  the  concentration  of  ores 
was  attainahle  with  small  qiianlities  of  oil.  quantities  so  small   that 
althougli  the  oil  coated  the  metallic  [larticles  in  the  exercise  of  the  well 
known  preferential  affinity  of  oils  for  metallic  substances,  the  coating 
was  so  minute,  so  nearly  Infinitesimal,  that  the  oil  disappeared  from 
sight  and  sense.     In  this  process  the  oil  coats  the  metallic  particles, 
modifies  the  water  so  as  to  produce  inruite  and  pci-sistent  air-lnihhles, 
and   increases  the   attraction   of  the        tallie  ^larticles   for  the   air- 
liulihles;  and  the  persistency  of  the  air-huhhies  is  such  that  the  air- 
buhl)les  ding  to  the  metallie  particles  and  carry  them  to  and  through 
the  surface  of  the  pulp,  and  when  the  air-hiihbles  escape  from  their 
water  environment  in  the  body  of  the  pulp  and  are  expo.sed  at  or  above 
the  stirfaee  of  tlie  pulp,  their  water-films  caixying  a  mineral  load  are 
maint'iined  intai't  until  at  least  their  S(>paration  from  the  body  of  the 
pulp  has  been  effect(>d.  by  overflowing  or  otherwise.     The  air-l)ubbles 
with  their  mineral  load  form  i'  froth  floatinsr  upon  the  surface  of  the 


rilK    KI.OTATIUN    I'liOCKSS 


:il 


IMilp,  whirli,  it'  allowfil  to  rniiuiii  thc-r-r  in  ;i  (|iiii'.sci'nt  rdnilition  will 
Hoal  for  ilays  and  weeks.  This  t'rotli  lias  tlierelnre  lieeti  pniperly 
called  a  i)efsist('iit  i>r  |)enniiiiciit  frotli.  It  will  always  form  a  eoherciit 
mass  >;t'  liulililes  pi'cssiil  ai;aiiist  eaoli  other  ami  l're(iiieiitly  several 
iiiehes  ill  thickness." 

This  deserii)ti()ii,  lackintr  adequate  piiiietiiatioii.  as  is  usual  in  h'^al 
statements,  may  he  accepted  as  otiicial,  beiiisr  the  ])rodiict  of  a  joint 
ef!"ort  on  the  part  of  coiin.sel  and  experts  representing'  Minerals  Sei)ara- 
tion  in  the  lawsuit  at  Wilminjrton.  In  the  basic  patent,  \o,  S.{.").12(). 
tlie  propoi-tion  of  oil  is  •riven  as  "a  fraction  of  ]';;  on  the  ore."  ^V.  H. 
Ballantyne.  patent  lawyer  for  Minerals  Separation,  testified,  in  the 
Hyde  suit,  that  "an  ideal  standard  for  the  afritation-froth  proee.-js  is 
Hto  2  11).  oil  per  ton  of  ore."  Mucli  les,s  is  used  now  in  the  liin  mills 
of  the  copper  mining  com])anies. 

The  proces.s  was  first  introduped  on  a  working  scale  in  the  Central 
mill  of  the  Sulphide  Corporation,  at  Broken  Hill,  as  already  men- 
tioned. Two  .veai-s  later,  in  1007,  it  was  adojjted  )iy  the  Zinc  Corpora- 
tion, to  he  discarded  during  l'»Of)  in  favor  of  the  Elmore  vacinim 
process,  and  to  ho  restored  again  to  favor  in  1011.    See  Fig.  0. 

The  next  important  application  wa.s  made  in  1012  at  the  Hraden 
Copper  mine,  in  Cliih',  where  a  200-ton  plant  was  erected.  The  ex- 
traction of  copper  (as  concentrate)  was  80  to  S.")';; .  Hut  when  a 
larger  mill  of  two  GOO-ton  units  was  Imilt  the  recovery  hecame  poor, 
lieing  no  better  than  it  had  been  in  the  old  water-concentration  mill, 
namely,  about  05';; .  Whereupon  the  oil  was  added  to  the  ore  in  the 
tube-mill  and  the  extraction  improved  at  once.  The  mill  has  now  been 
enlarged  to  seven  600-ton  units,  treating  o.jOO  tons  per  day."  The 
extraction  last  year  was  77  per  cent. 

In  February  lOlf)  the  Anaconda  Copper  ^Mining  Company  took  a 
license  from  Minerals  Separation,  and  at  that  time  also  the  Tiisj)ira- 
tion  Consolidated  ('opper  Company  made  an  agreement  for  the  same 
purpose.  Roth  companies  built  large  mills  for  the  operation  of  the 
process  during  last  year."''  The  Anaconda  now  treats  12000  tons  and 
the  Tnsj)iration  8000  tons  of  ore  daily  by  flotation. 

The  first  mining  company  in  America  to  ignore  th(>  Minerals 
Separation  patents  was  the  Butte  &  Superior,  in  Montana.  Under 
the  technical  guidance  of  James  M.  Ilyde,  this  company  built  a  loO-ton 


i  ::t:  xir:;;!";;  a::::.      .i::r;;My  iJuCl  :<CiC}iTiflc  i'i'tss.   LKrceliiuei    i5,  iitlo. 
♦^'Flotation   at   the    Inspiration    Mine,    Arizona."     Minitiff  and   Scientiflc 
Press.    .Inly    3,    1915.      Also    'Flotation    at    the    Washoe    Reduction    Worlis, 
Anaconda.'    By  E.  P.  Mathewson.    if.  tf  S.  P..  August  28,  191 :. 


Till,  iliumiiin   njiiri,-.- 


"""    '"   'l„.,r   n,,||   ,|„,,n,.    I'MJ.      n,,,   |,,,„„|^,.,|   ,,,„   ,i,.^,    ,„^,    „^^^^    „ 
Ulllrl,    IS   nnu    I..  |,„V    III,.    S|||, ,•,.„„.   CMiri    nf   tl,..    I    ,,,,,.,1    S|;i|,s 

'"ll'l-   "■llll'fllll.s     ■lialu'r,!    will,    ihtrillir..„|,.||I    ;irr    III,.    ||;,|l    ('„,,,„.,• 
.Vv;„|;,  (•n„s.,|„|al,.|.  .Mmu'i,,,-,  (  ■„,,,,.,•.  ;„„|  tl„.  .Mian,,       Thr  fiisl    li.ive 


KKi.  '.*.     nil.  moniiMi  run,  kss  in  hik  .kmkm.   mm.,.. 

u.v  tiir  .laniu.y  ,iKirl,i,u.  ami  th.  last  on.,  tin-  Callow  pinnimati.- 
hnuuUv.  In  ,.,.1,  ,as,.  ii  is  .stat.,!  tliiit  the  Miiu-nils  Separation  nui- 
cliiiu.  -HI  whi,-h  viol,.|,t  a^'iiatioM  i.s  ,.ff,Tt(.d  l.v  l>lM.l,..imp..ll,.,s-wa.s 
tn.'.l  hrst  a,„l  then  .lis.ani..,!  a.s  in.tr.rfiv...  Tli.  pneuniati.  flotation 
I'iant  at  .Miami  was  con,,,,,.,,,...,!  i„  Aii-iist  1!IH  and  n-modt'lrd  in  th- 
.ai-ly  part  of  l!!]",.  Suit  for  infrinK..m,.nt  was  lirou-ht  at  on,-,,  hv 
.Arincrais  Separation,  the  trial  <-omiii..n,-insr  on  March  29  and  ...idin'.r 
"11  -May  L>..  111]:..     Tim  ,l,.,.isioii  of  the  Court  is  not  yet  known. 

..^Minerals     Separanon.     Mniited.     and     .Minerals     Separation     Ameriran 
S,vn(iii...ite.  I,im:ted,  r.  .lame.s  M.  Hyde. 


rifi:  ^ r.ur \iiuN   I'liociss 


S.i 


\s  apiiliiil  at  Miai'ii  III.-  fldtation  [jhu'i'ss  is  siiniilili.il  In  the  iisr  of 
a  laimil.r  haviiiL'  a  raiiva.s  iMilioin  llinmu'li  uliii'li  ait-  is  toiv.wl  iiiwliT 
imssi.n'.  This  ciM's  tlir  ".ms  r.Miimvd  for  \\i,-  i:rii.Tatioii  ,,|'  l,iilil,|,.s 
ill  a   pulp  pn^vidiisly  inn,|ilir,|   |,y  tlir  a<Mitinn  nf  ,,||.  ulijrh   is  iiiiv.'d 

"■i"i    '' '■'■    "liil''    li'iiii:   piiriip.MJ    nit,,   a    i'a.liiica    tank,    of    itrowii 

au'italnr.   ulicri'   it    iiiiilrrpi.'s    I'lirtlicr  riniilsiJlratioM    lii'i'.n-c   ctitcriiiir 

llir  ( 'all(,u    laiiml.  r  .■,,iistitiitii,L'  thr  tlntalioiirrll.      It   is     laii I   that 

tliv  t'rnlli  |ini(lnci.,l  in  this  way  is  liitTiTfut  Inun  that  maiir  in  thr 
iii.'<-haniral  nii\,r  ol'  lli.-  .Min.|-als  Separation  inarMiio.  In  ihr  ,.iir 
rasr.  a.NdnJini,'  to  |{.  ( '.  (  'aiihv  the  rroili  consists  o|'  a  mass  ot'  .Icliratc 
IraL'il'-.  and  .■vaiicsci'iit  liiihhj.s.  xvlih-h  rise  to  tin'  sMrl'ar,.  in  rapid 
siiri-.'s^ioii  ami  maintain  a  I' roth  only  lifi^aiisi'  tiny  are  I,,',  <'j  ■.'encratid 
slijrhtly  faster  than  they  luvak.  so  that  the  iip|)ermost  layer  overtlous. 
with  its  l.iirden  of  mineral,  over  tin'  lip  o|'  ih,.  vessel.  In  the  other 
las,'  the  froth  is  said  to  |,e  '■thi'-k.  eolierent.  ami  persistent."  as 
.Mr.  I'ieard  i)hras.(|  it.  "  It  appears  as  if  thi'  mini^rals  weri'  protei-tin'.' 
till-  teiMJer  air  hiihlile  likr  an  armor,  and  insti^ai!  ol'  destroyinir  it.  wer  ■ 
actually  triiardintr  it.  Thf  froth  has  a  lontr  life.  I  liav.'  myself  seen 
a  froth  standintr  for  •2^  hours  witliouf  the  h^ast  chaiiu'e  liavin<r  taken 
plac'e."  So  teslitii'd  Dr.  Adolf  Lichmann.  .Mr.  Hallantyne  stated 
that  this  ajjitation-froth  of  ih,.  .Afincrals  Separation  machine  was  so 
dense  that  it  would  sujiport  a  spade.  Mr.  Canliy  shoved  that  the  air- 
froth  of  the  Callow  iiiaehiiit'  would  not  support  a  mat(  h-stem. 

Kro.i;  •:  foreiroint;  sumii:ary  it  is  dear  that  tliive  pro<'csses  are 
covered   liy  the  trenend  term  'tlotalion.'  and  that   to  clarify  the  ,lis- 

eussion   of  the   suliject    it    will    he  Well   to  distiniTuish    hetweeii 

1.      Kilm-siispeiision.  as  in  the  \Voo,l  ami  .Mac<|uistcn  methods. 
2      Oil-flotation,  as  in  the  Rol.son  and  HImore  hulk-oil  methods. 
■  1.      i'.ulihle-levitation.  as  in  the  Klmore  vacumii.  Delprat.  Froinent. 
and  Sniman-l'icard  methods. 

The  third  class  can  lie  further  suh-divided  aceordintr  as  carhon 
dio.xide  or  air  is  the  priueipal  gas  utilized  f(u-  makintr  huMihs. 

Finally,  the  air-huhhle  methods  can  lie  idassifieil  accordin-.'  to  the 
way  in  wliieh  the  air  is  introdiicoil: 

'  1  From  the  bottom  of  the  ves.sel,  as  in  the  Callow  and  Owen 
rells. 

(2'  l?y  heing  entrained  or  drasrsred  into  the  i)nlp  hy  the  heatiiiK 
of  paddles  or  .some  other  form  r^  iipeller.  as  in  the  (iahhett  and 
Hoover  mixers. 

(.3)  By  escape  from  solution  in  water,  as  in  the  p:iiiiore  vacuum 
maoliinc  and  the  Xorris  apparatus. 


34 


Tin:    KI.dTATMX    I'KOCEt-S 


It  irnuiins  to  rniplia.si/r  tlir  fact  tliat  fnnii  tlic  liijrli  i-atio  of  :'.  tons 
of  oil  prr  ton  of  or,.,  tlir  prop,,,-!],,,,  of  oil  usr.i  in  flotation  lias  do- 
creasf.l,  liy  ivason  of  tlir  ivro-rniti„„  of  ih,.  part  play..,l  l,y  air.  to 
"iH'-liiinl  of  a  pound  pn-  ton  of  ore;  that  is,  ono  ciKliti'fn-tliousandtlis 
of  the  quantity  iis<.,l  hy  Rol,son.  Con.Mnivntly  tlir  a. -id  nscl  has 
dcprfascd  to  a  iriinus  (piantity.  namely,  alkalinity. 

Tin:  rATi:NT>,  This  is  tli,'  part  of  thf  .snltjcrt  of  which  w<>  liav 
li'ii'-d  th.'  most;  ind.vd,  until  rcrently  tho  literature  of  the  flotation 
process  was  closely  idenlilie.l  with  the  records  of  patent  litif,Mtioii. 
That  IS  why  tho  scientitic  i)rincii)les  are  as  yet  so  little  under- 
sto,,d  and^the  technolofry  of  the  process  lias  made  such  scanty 
pro^'ress.     The  aim  of  a  pati'ut  spteifieation  is  to  dis(dose  just  enough 

to  prove  originality.     In  many  cases  this  has  I n  done  to  tlie  apparent 

satisfactioi,  of  the  E.xaminer  of  Patents  without  conveyinfr  all  the 
fai-ts  es.sential  to  a  dear  uiiderst;ui,lin^'  of  the  oi)erations  involved. 
The  description  given  in  a  modern  patent  is  cryptic;  it  is  couched  in  a 
'jiiasidegal  .jarg:)n  that  as'^ists  ohfuscation.  I  refer  to  jiroces-scs  only, 
for  th<.  disputes  over  flotation  patents  have  arisen  over  methods  not' 
machines.  The  apparatus  required  had  already  heen  used  in  w..,er 
branches  of  wet  metallurgy,  so  that  we  have  heei:  .si)ared  one  source 
of  troulile.  at  least. 

The  litigation,  which  is  new  ;i  .serious  ohstacle  to  ttie  free  develop- 
ment ,,f  the  jiroeess,  has  arisen  largely  from  confusion  of  ideas  as  to 
the  underiying  causes  of  flotation.  The  patentees  did  not  understan.; 
the  phenomena  with  which  they  played.  Those  to  whom  they  .sold 
tlieir  patents  knew  ev „  l,..ss.  Tl;,.  inter]. retat ions  of  attorneys  and 
judg.'S  have  elucidated  the  law  hut  c„nfused  the  physics,  xi)  clear 
Hd.iudi.'ation  „f  rights  is  possible  so  long  ,,s  claims  and  cminter-claims 
are  ha.seil  on  an  ignorance  of  the  rationale  of  the  process. 

As  th.'  flotation  jirocess  of  today  is  es.sentially  that  of  making  a 
minoral-huoying  froth  in  modified  water,  it  is  not  necessary  for  im'to 
maie  further  reference  to  the  patents  granted  for  tlie  use  of  purely 
surface. ten.sioii  effects.  It  would  serm  pernii.ssihle  also  to  omit  further 
consideration  ,,f  the  hulk-oil  methods.  Imt.  as  a  matter  of  fact,  none 
of  the.se  oi)erated  withoul  the  aid  of  air.  although  the  patentees  were 
quite  nimware  of  it.  and  it  was  from  th.^s.^  hulk-oil  methods  that  the 
frothing  proci>ss  was  developed    fortuitously. 

The  first  patent  for  the  use  of  oily  suhstances  and  .•  lal-tar  iiroilucfs 
in  the  concentration  of  ores  was  that  granted  to  William  Haynes.  an 
Engiisiiman,  in  iStHi:  iuit  tins  is  now  only  of  academic  inferesf.  Next 
comes  the  p;itenf  of  Carrie  .1.    Kverson.  dated  August  24,   ]S,s(i.   the 


TtlF.    II,(iT\TI()N    THdCKss 


35 


application  having  Ixrn  tiled  on  Au!,'ust  L'!t,  18Sri.-'"  Thr  Evcrsoii 
patent  ret'ei-s  to  the  seleetive  aetioii  of  oil  for  "nietallie  siihstances" 
and  the  inerease  caused  in  that  select iveness  hy  the  addition  of  iicid. 
The  pulp  is  stirred  so  as  to  hrinrr  "the  mineral"  in  contact  with  tiic 
oil  and  acid,  producing,'  a  -'stirt'  mass."  The  us(>  of  ■'iiliout  ;i  li.irnl 
of  oil  to  the  ton  of  ore"  is  mentionecl.  indicjitinir  a  ratio  of  nliout 
17'~;.  Other  statements  indicate  that  she  used  as  little  as  ")','  of  oil 
|)er  ton  (,f  ore.  The  sei>aration  of  the  oiled  mineral  from  the  unoih'd 
i-'iuisjue  is  described  thus:  "In  j)r!ictice,  the  concentrate,  after  thoroufrli 
afiilation  of  the  mass  iuid  detachment  of  the  sand,  will  in  this  case  be 
preferably  removed  by  meiiiis  of  a  constiint  overflow  of  wider  from  a 
washinsr-out  ves.sel.  I)y  win  li  overflow  tii.  concentrate  will  be  floated 
off."  These  la.st  words  constitute  the  only  direct  refcn'Mci'  to  the 
floating  of  the  conecidrate. 

A  great  deal  more  has  been  read  into  this  patent  Ihiui  could  ever 
have  been  in  the  mind  of  the  patentee.  Tt  is  ditficult  to  ri'ad  her  de- 
s(>ription  without  cocking  one  eye  at  th"  present  practice  of  flotation, 
whereliy  some  of  Mrs.  Everson's  phra.sing  is  given  a  significance  to 
which  it  had  no  possibl.'  claim  30  years  ago.  The  proportion  of  oil 
used,  even  the  maximum,  would  not  sutTfice  for  the  operation  she  had 
in  mind,  namely,  the  floating  of  the  he;ivy  sulphides  by  dii'cct  aid 
of  the  buoyancy  of  oil.  Iler  maxinuim  proportion  of  oil  reiti-escnts  a 
m(>re  fraction  of  the  (piantity  re(|uired  for  this  operation.  She  dis- 
closed no  notion  of  the  assistanci'  to  be  obtained  from  air.  in  tiie  form 
of  bubbles,  althousl'..  of  course,  tliis  was  her  principal  flotative  agent. 
The  process  described  by  her  is  quite  imiiraeticable  on  a  large  si-ale. 
and  it  never  was  operated  .save  in  a  crude  experimi'ntal  way.  \ever- 
theless  the  exigencies  of  patent  litigation  have  caused  the  opjionents 
of  Jlinerals  Separation  to  idealize  both  ilrs.  Everwm  and  her  metal- 
lurgical adventure,  as  they  have  also  created  a  romantic  story  of  the 
supposed  epoch-making  discovery.  She  is  represented  as  a  school- 
teacher, a  Jliss  Everson,  who.  as  the  sister  of  an  assayer.  washed  some 
greasy  ore-sa<'ks  aiul  s;iw  the  sulphides  floating  on  the  contaminated 
water.  Even  the  idea  of  agitation  was  suggested  by  the  activity  of  her 
hands  in  the  wash-tub.  Therefore  "it  only  required  the  customary 
acuteness  rf  observation  of  the  Western  lnd,\'  school-tenclier  to  grasp 
the  es,senl  al  facts  of  sulphide  flotation."-'  This  is  pretty,  but  not 
scientific.    The  "essential  facts"  are  a  bit  too  slippery  to  be  grasped 


iii]ruiuiui.   «i3    ufiu^   lilt*  one    iruni 


which  priorit.v  of  iiivpntion  is  nioasiired. 

2i'Concentrating  Ores  by  Flotation.'     Page  5. 


36 


TIIK    FI,nr\'IMN    I'KciCESS 


liriiily  cvni  to,i;iy.  In  tliiiikiiiu'  ari,|  necessary,  sli,.  was  wi-oi;  It  is 
l<iio\vn  iinw  not  to  lie  an  essential.  Kven  the  use  of  oil  as  a  diivct 
in.-ans  of  Inioyaiicy  has  receded  into  the  hack-L't-oiin  I ;  if  she  liad  un- 
derstood the  rationale  of  her  own  operations  she  wonid  have  known 
that  it  was  not.  so  iinieli  tiie  selective  adhesion  of  the  oil  to  ih.'  mineral 
particles  that  trav,'  ln-r  the  requisite  huoyancy  as  the  prreater  seleetive- 
ncss  of  the  an-  hnhhlcs  made  l)y  airitation  in  water  nioditied  l,y  the  oil. 
Carrie  .Jane  Everson  hail  no  idea  of  the  frotiiinj,'  process.  Her  nietlrnds 
may  have  invoUvd  hnlil.icdcvitation.  Imt  she  did  not  know  it.  and  her 
de.scriplion  would  not  su<r<rest  it  to  anyone  not  ver.sed  in  much  later 
knouhMlu',..  The  elVort  to  feature  this  lady  as  the  inv..ntor  of  the 
IrothiuL'  jiroeess  cannot  commend   itself  to  an  unprejiniieed  student 

of   till'    Slllljcct. 

It  is  iiiieivsiini.'  to  add  that  tlu'  --Aliss  Hverson"  of  the  story  was 
really  a  Mrs.   F-Avrsoii  :  the  wif,.  of  a  Chieaixo  doctor:  she  was  not  a 

■'''■' l-''';i''iicr;  her  lonUicr  was  not  an  assayer:  and  there  is  no  reason 

lor  i-e-ardinir  the  story  o,  ;lie  ore-sacks  as  anythinsr  more  than  the 
tiction  of  Mil  irrcsp.msihle  scrilie.'-  .Mrs.  Kver.s.m  died  at  San  An.s,.lmo. 
Califofiii;!.  on  Xovemlier  :!.  11)14,-' ■ 

Next  c'omes  the  liritish  patent  of  .(ainiary  S,  ]S!)4,  jjnurted  to 
(;eori.'e  Rohson.-'  an  Hnjrlisliman.  wlio  did  his  experimental  w(U'k  at 
the  same  place  and  on  the  same  ores  as  the  Elinor.'  lirothers.  at  the 
<;iasdir  mine,  m-ar  1)ol<rclly.  in  Wales.  He  disclaimed  "the  use  of 
fici,ls  or  .salts  an.l  also  the  metlio.l  of  wa.shini.'  away  the  fraiifrne  with 
water."  etVectiinr  ••i],,,  separation  of  the  metallic  matter  by  the  mix- 
ture of  oils  alone."  He  does  not  specify  ih,.  <|uantity  of  oil.  Imt  T 
am  informcl  that  it  was  in  the  ratio  of  :! ;  1.  three  tons  of  ml  !o  one 

"''"'■'■•      '''lii^   ":i-^   li-'ic    hulk  oil    flotation    and    it    proved    an    ah.jeet 
failure. 

Then  came  Francis  Edward  Elmoiv.  on  April  10,  ISno,  dni'lieatiii-.' 
his  I'.riti^i,  p;,ici,t  of  Octohcr  ]S.  I.^'ts.  His  nictlmd  has  l.een  .leserihed 
already,  li  ,,nly  remains  to  sav  that  in  .so  far  as  this  meth.id  proved 
more  practicahle  than  that  of  l;,,hsoii.  the  result  was  due  t..  the  fact 
that  the  Elmore  hrothers  were  eapahle  enirineers  and  therefor.'  ,!.■- 
si-.'n.M!  a  m.uv  suiiah!.'  plant.     Th.'  pat.'iit  i.L'ii.uv.l  tlm  us,'  i>f  air;  tii.' 

int.'iiti.m  was  not   t.i  emulsify  il il  aii.i  ii.it  to  a. 'rate  tli.'  pulp,  hut 

this  thi'or.'lii'al  .'ondition  was  n.'ver  fiillille.l,  as  is  clear  from  th.'  fa.'t 
that  Ih.'  flotative  a.-ti.in  was  loO^;    nmre  than  that  .'ah'tilalil.'  fnim  th.' 


--Tn    file    i'i  nntn  inj    Tr;}}-'.<^.    V.::yrh    ?.     10f:'^ 

-■''Tlie  I'.'vei-'-on  Mytli.'     MitUnii  nii<l  Siirntiflr  Press.  .Tanii.'iry  l."i.  tntfl. 
-<His  Anicricaii  patent  is  dated  .lamiar.v  13.  1897. 


TlIK    KI.oTATION    l'l<()(h> 


37 


ditiVrcniT  of  spccitic  firavily  lictw.Tii  tlu'  oil  and  tlic  water,  On  .Janu- 
ary :{.  llili.i.  A.  Stanley  Elmore  took  out  a  Hritisli  ])at(nt  for  an  aj)- 
paratus  Jor  excluding'  tiic  air  dnrin^  the  operation.     He  et^'ccted  his 

purpose  hy  sealiuf,'  all  the  open  vessels  witii  a  rinjr  nr  surla( f  oil; 

from  wiiieh  it  is  evident  thai  at  that  time  he  and  his  brother  en- 
deavored to  base  their  method  wholly  on  hulk-oil  flotation. 

Ill  January  1!)02,  Charles  V.  Potter,  an  Australian,  obtained  a 
Uriti.sh  j)atent  for  tiu'  flotation  of  sulphides  in  a  hot  acid  solution. 
He  used  a  stirrer,  and  he  claimed  that  the  solution  would  '■react  on 
the  soluhle  sulphides  present  to  form  huhhles  of  sulphuretted  hydro- 
i.'en  on  the  ore  particles  and  thereliy  raise  them  to  the  surface. ■-' 

In  Novemher  of  the  .sa-ue  year.  \'M)2.  (luillauiiie  I).  Delprat.  the 
mana^'cr  of  the  Broken  Hill  I'roitrietary  mine,  applied  f(u-  a  similar 
patent,  except  that  he  used  salt-cake  instead  of  sulpluiric  acid.  Liti- 
jration  ensued,  t'ollowed  hy  a  eompronii.se.  eliminating'  Pott'r.  fn  later 
patents  hotli  Potter  and  Delprat  introduceil  the  use  of  oil.  finding  it 
henetieial. 

In  his  first  American  patent.  No.  7.i").n71.  tiled  on  January  2.  100:!. 
Delprat  states  that  the  pn-css  "depends  upon  the  ore  particdes  heing 
attacked  liy  the  ai'id  to  f.uiii  a  gas.  Each  ore  particle  so  attacked  will 
have  a  huh!ilt>  or  hul)l)les  of  gas  adln  I'iuir  to  it.  hy  means  of  which  it  will 
he  floated  and  can  I)o  skimmed  or  floated  off  the  Jution."  ("Ore 
particles"  means  blende  and  galena  at  Broken  .till.)  Here  is  a 
pretty  good  recognition  of  bubhle-levitalion.  only  he  sujiposed  the 
sulphides,  not  the  gangiie,  to  })e  attacked  hy  the  acid.  Tii  another 
|>lace  he  says  specitically :  "The  sulphides  in  the  ore  are  rapidly 
attacked  hy  the  acid  and  gas  bubbles  formed  on  them,  that  (luieklv 
carry  them  to  the  surface."  Tn  this  patent  he  claimed  the  use  of 
nitric  acid  and  a  suitable  nitrate,  such  as  sodium  nitrate,  the  latter 
being  intended  "to  inerea.se  the  specific  gravity  of  the  bath."  AVhat 
reaction  was  to  follow  between  the  sul])liides  and  thi'  dilute  niti'ic  acid 
is  not  dear.  It  has  lieen  recorded-"  that  in  the  early  days  of  the 
Potter  Delprat  methods  it  was  suiipo.scd  that  the  ai'id  liberated  hydro- 
gen sulphide  from  the  sulphides,  when  s\di)huric  acid  wa.s  used,  with- 
out attacking  the  gangue.  Those-  who  first  scouted  this  idea  suggested 
that  cnrbon  dioxide  was  generated  by  decomposition  of  a  carbonate 
coating  on  the  sulphides.  (bu>  to  weathering  of  the  ore,  arguing  there- 
from that  it  was  necessary  for  the  gas  to  be  produced  at  the  surface  of 


-■"■The  t'h.vsirs  of  Ore  Flotation.'    B.v  .T.  Swiiihiirnp  and  C.  Ruilorf.     Muiing 
and  Scirntifir  Press,  February  24,  190G. 


38 


HE   FLOTATION-    I'ROCESS 


till-  siilpliiclr  particl.  s  themselves.     All  ot'  tlieso  expUiiiatioiis'"  are  now 
mi  !li(>  s.-rap-hrap  of  ilivanled  tlicorifS. 

Tiiesc  patents  .a'  I'niter  and  Helpfat  liave  lieen  lalielled  variiinsly 


fr^ 


O^erfhtv  forConcentrate. 

'jii  "7 


ieod  BffflePlafe^. 


Pocket  for^afthinq 
atones,  bott^  ett.  - 


Meta/  :ieat  — ' 


Fn,.  II).     Tiih;  I'oiiKK  AI'r.viulL> 


luuler  'aei(l-Hi)tati()ir  ami  "sni-laee  tension'  nietlnuls.  Uelprat's  ap- 
paratus does  indeed  sugrgi'st  a  proeess  ot'  tli(>  Rradford  or  Wood  type, 
but,  of  course,  l)otli  he  and  I'otter  depended  for  their  results  on  the 


2'In  his  book  Mr.  Hoover  states  (page  13,  second  edition)   tliat  Goyder  & 
I^.iiigliton,   in  tlieir   patent   of  ,Iiil,v   31,   l!t03,  "were  the   first  to  disolose   the 


THE    FI.OTaTION'    PltOCESS 


39 


lilicratioii  of  ciulioM-dioxidt'  gas  I'rom  the  gangiio,  wliicli,  at  Hrokeii 
Hill,  foiitains  a  larso  i)n)i)nrtion  of  (■arl)oiiatcs,  iiotal)ly  ealciti'.  sid- 
erite,  and  rliodocrositc  From  any  of  those  a  hot  sulpliiiric-ar'id  sohi- 
tion  would  release  the  gas  that  proini)tly  attaeheil  itself  t(,  the  iiietallii' 
surfaces  of  the  galena  and  blende. 

-Meanwhih"  Alcidr  Fronient.  in  Italy,  had  -rot  hold  of  the  liuMih- 
idea,  'vhieh  is  the  real  ba.sis  of  the  flotation  process  as  it  is  understood 
today.  He  invented  his  method  in  IDOl  and  tiled  his  claim  for  a 
British  pate.it  on  June  9,  1!)02.  This  patent  was  duplicated  in  Italy, 
but  H'll  in  the  United  States.  The  fact  last  mentioned  is  important. 
Fnimeiit  claimed  that  his  process  was  '\a  moditieation  of  what  is 
known  as  the  oil  proces.s  of  ore  concentration."  meaning  that  of 
Elmore,  for  the  hulk-oil  method  had  been  tried  at  the  Traversella 
mile,  in  Italy,  where  Froment  was  engaged  as  an  engineer.  Ilis  plan 
was  to  generate  bubbles  of  gas  by  the  reaction  beiween  sulphuric  acid 
and  the  carbonates  in  the  gangue,  adding  limestone  when  the  ore  did 
not  contain  enough  carbonate.  He  argues  that  ''if  a  gas  of  anv  kind 
is  liberated  in  the  mass,  the  bubbles  of  the  gas  become  coated  with  an 
envelope  of  sulphides  and  thus  rise  readily  to  the  surface  of  the  Iiqui(' 
where  they  form  a  kind  of  metallic  magma."  It  will  be  noted  that  he 
says  "gas  of  anij  lind."  As  the  children  say.  in  a  familiar  game,  he 
was  "very  warm"  .just  th(>n.  for  he  bad  only  to  invoke  the  aid  of  air 
to  havr  described  the  es.sential  principle  of  the  later  phase  of  flota- 
tion. He  also  states  that  the  sulphide  particles  when  "moistened  by  a 
fatty  substance"  have  a  tendency  "to  unite  as  spherules  and  to  float 
upon  the  surface  of  the  water."  His  brief  description  closes  with  the 
statement  that  "the  rapidity  of  the  formation  of  the  spherules  and 
their  a.seension  is  in  direct  ratio  to  the  qiiantity  of  gas  produced  in  a 
given  time."  As  to  the  oil.  the  only  mention  of  quantity  is  made  in 
describing  a  test-tube  experiment  in  which  he  uses  "a  thin  layer  of 
oil,"  This  phra.se  has  been  variously  interpreted,  according  to  the 
exigencies  of  litigation,  but  it  refers  obviously  lo  a  minute  prop.irtion. 


principle  governinK  Potter's  and  Delprafs  ncidflotation  process,  namely,  that 
the  action  of  the  acid  on  the  ore  generated  Kas-bubbles  to  which  the  sulphide 
particles  attach  themselves,  and  were  ttoatod  to  the  surface,"     What   they 
said  was  that  "the  physico-chemical   action  develops  the  formation  of  g.is- 
bubbles  adherins  to  particles  of  certain  of  the  finel.\  'livided  minerals  and 
causinc;  such  particles  of  certain  minerals  to  rise  to  or  near  the  surface  of 
the  solution."     Rut  tb!s  i\c\c^  mt  msV—  *f  ri^i^r  th^t  tv-..~.  v.-.-.!,!. ;.-...  ......  ..i.;..:...^.' 

by  the  deconiiwsition  of  the  carbonates  in  the  gansue;  it  is  more  nearly 
compatible  with  nelpiat  s  idea  that  they  were  generated  by  the  action  of  the 
acid  on  the  sulphides  themselves. 


40 


TIIK    FI.U'lAlluN    I'KDCESS 


In  tlic  (lirtTtidiis  ^'iv.ii  liv  liiin  In  ilir  .Miiirmls  S,|,iir:iti(iii  pcnj)!,.  when 
llifv  ti(ai^'lit  liis  iiatrni  ri<:lits  mi  Xdvciiilicr  17.  l(Mt;i.  Ii,.  sin'cilii-d  ]'; 
of  niiiirral  ciijuriiie-dil  lor  on-  (•(iiitaiiiiii;.'  up  1o  ,')';  ot"  iiiclal.  1  ',  of  oil 
for  ore  cohtaiiiin^'  in',,  ami  so  on.  up  to  or'cs  coHtaininir  o^',  of 
ni.'tallic  lead,  wliich  woiiM  rcipiii'c  :!^';  of  oil.  .\s  oil  flotation  was 
uiidcrstodd  at  that  timr.  this  marked  a  irreat  rciluetioii  in  the  pro- 
portion of  oil.  However,  the  luoro  iiitercstiiiir  ])oint  is  Fron.ent's 
failure  t(.  jiereeive  the  possibility  of  usinp  air  as  the  tras  for  niakinix 
liis  liuhliies.  He  <|.'pended  upon  eheiiii-al  aetion  to  furnish  him  with 
the  ne(e>sar.v  >,'as.  Xevertlieh^ss  Fronienf  desei'ves  a  liijrli  i)laci'  in  the 
roll  of  flotation  |)ioneers.  for  he  made  an  important  ste|)  forward.  He 
fui-nished  the  link  lietween  liulk-oil  and  air-froth  flotation. 

Till'  next  elia|iter  in  the  story  marks  a  nt  infrression.  ("mler  date 
of  Xovendier  L'.s,  l!)(ii>,  Arthur  Iv  ( 'atteriiiole  ohtaiiied  Hrii  sli  patents 
No.  2(k2!).')  and  Sfl.L'fKI.  hdth  i,f  which  were  aeipiired  hy  John  Ballot 
and  associates  in  Dec'inher  l!Mi2.  preparatory  to  the  formation  of  the 
company — Minerals  Separation.  Ltd.— orjranized  to  exploit  them. 
In  .\utrust  IIMC!  Cattermole  revised  and  ami>liHe(l  his  jjrevious  claims 
in  I'-rilish  iiatent  No.  iS.oS!!.  which  wa.s  duplicated  in  the  Cnited 
States  under  date  of  Septemlier  2S.  lOn;!.  as  N'o.  777.27:5.  This  last 
is  the  principal  j-atent  eoverinjr  flie  so-eallcd  jjrranulation  i)roi-ess, 

( 'attermole  prefaces  his  ilescrii>tion  hy  refercnee  to  tlio  seleetivene.ss 
of  oil.  when  ennilsitied.  feu-  sulphide  partiides.  such  selective  action 
I'eini:  intensified  liy  the  acidnlation  of  the  water.  He  IIkmi  proceeds 
to  say  that  if  the  mi.xture  h..  tlinroufrhly  asritated.  there  is  a  tendeney 
for  the  metallil'erous  partiides.  now  coaled  with  oil.  to  adhere  toirether. 
fornduu:  ^'rainiles-^  ihat  sink  and  are  readily  s.'parated  from  tiie 
licliter  f'ans/ue  liy  an  up-current  of  water.  \u  his  deseription  of  the 
op.  ration  he  .says  that  "the  pnmules.  with  a  certain  amount  of  heavy 
sands,  sink  to  the  liottoin  and  aie  disehartred  [see  Fipr.  11]  throntrh 
a  pipe  (;'  into  the  vessel  A',  whih'  the  lijrhter  sands  are  carried  away 
by  the  upward  current  and  discharfied  tliroutrh  outlet  (!-  to  a  lifrht- 
sniuls  taid<  J."  In  the  (lrawin<r.  A',  A-.  A\  W  A',  and  A"  are  miNin^ 
vessels;  (;  and  K  a!-(  classiliers:  K  is  a  tank  cor.faininfr  oil  enuilsion. 
He  refers  to  the  quantity  of  oil  several  times  in  vasrne  terms,  exjilain- 
iiip.  however,  that  it  should  be  "insufiicient  to  materially  les.sen  the 
specific  irravily  of  the  met'dliferous  mineral  j)artieles."  Finally,  he 
specifies  the  proportion  as  "usually  an  amount  of  oil  varyinfj  from 
4Tr  to  (>''(  of  the  weisjlit  of  metalliferi^us  niiiieral  matter  l^rese!!*  in 
tlio  ore."     This  can  be  interpreted  variously:  if  it  refers  to  tlie  sul- 


-sThe  '«raniiles'  nuiv  he  rnntr.-istid  with  Froniem's  ■s|ilienilps.' 


THE    KI.DTATION    I'KOCKSS 


41 


phidi'S  to  1)1'  C'oiicciiti-iiti'il,  llieii  iiii  <iiv  ciiiitaiiiilif;  lil)','  Iilfiidi'  wmild 
rfiiuii'i'  fniiii  (1.8  to  1.2','  of  oil.  (•(|uivali'iit  to  from  1(1  to  24  ili.  oil  \Hf 
toil  of  ore.  Oil  the  otluT  hand  a  2^7  clialcocite  ore  would  lu'cd  only 
l.ti  to  2.4  II).  ot'  oil  ])rr  ton  of  ore.  whidi  is  as  little  as  is  now  usimI. 

This  Caltennole  |)roees.s  \  as  the  snh.jeet  of  leiif^th.v  experiiiierit  in 
the  Lond'in  lalici'ator.s'  of  the  Miiieriils  Sei)aration  eoiiijtan.v.  where  all 

No.  763.559.  PATENTED  JUNE  21,  1904. 

A.  E.  CATTEEMOLE. 

CLASSIFICATION  OF  THE  METALLIC  CONSTITOENTS  OF  ORES. 

ArrLioiTioi  riLCs  icrt.  ».  i>oj 


JUtfi:: 


Fig.   11.      THE  CATTEBMOLE  PATENT. 


42 


TlIK    I-I.OTATIUN    rUKCESS 


sorts  of  Viiriatioris  in  tcinpcnituiv.  n.-iililirjitioii.  oilm^r,  ;,ii,l  luixiiiK 
wnv  tri.d  l,y  Artlnir  H.  ni^'j.'ins  iimlrr  diivctions  from  II.  L.  Suliiian 
Jiihl  11  K.  K.  I'i.anl.  It  was  not  iiii  il  ,Maivli  ifKT),  ilia'  is,  , .rally 
•2\  yrars  sii!,;-fqu..i,t  to  the  pati'Mtiiif;  of  the  Cattonnol,'  mr.liod.  that 
it.  was  found  advisable  to  float  the  -{.'ranulcs'  .-atlirr  than  sink  thmi, 
wluTvnpoii  ensued  ••||m-  staitliufr  discovery  ,,f  the  airitation-frotli' 
l>ro(ess."'  as  \V.  II.  Haliantyne  lias  des.rilied  it.  A  sinnhii  iliseovery 
was  made  eontemporaneousiy  at  Hroken  Hill,  hut  there,  ac-onlinu'  to 
James  Ilehhard.  it  was  not  so  "startliuir ;"  it  was  the  ivsidt  oi'  strenu- 
ous eir.irts  to  make  a  workable  proeess  out  of  the  imi)ractieahle 
method  devised  liy  C'attermole.     Sot!  Fip.  12  and  14. 

This  'diseovery'  led  to  Minerals  Separation's  hasie  jiatent  T'.  S. 
No.  835.120.  of  May  2!».  im').  whieli  duplieated  the  P.ritish  patent 
\o.  TSO:!  of  April  12.  l!l(i.-),  taken  nut  in  the  names  of  H.  L.  Sulman, 
II.  V.  K.  Picard,  and  John  Hallot.  In  this  patent  the  aid  of  idiemieally- 
t'enerated  fras  is  discarded  definitely,  in  favor  of  airJmhhlcs.  'I'his 
.seems  to  me  a  matter  of  far  jrreater  importanep  than  the  reduction 
in  the  proportion  of  oil.  The  patentees  say:  "It  is  to  he  understood 
that  the  oiijeet  of  usinj,'  acid  in  the  pulp  aecordinjr  to  this  invention  is 
not  to  l.rinfr  about  tli.'  froneration  of  ^'a,s  for  the  purpose  ,d"  flotation 
thereby,  and  the  proportion  of  neid  used  is  insnflicient  to  eau.sc 
ehemic-al  action  in  the  metalliferous  nnnerals  prcstMit."  This  ditTeren- 
tiates  the  UK^thod  from  those  of  Potter.  Delprat,  Froment.  and  Do 
Bavay,  the  addition  of  acid  beinsr  therel'ore  presumably  to  assist  the 
.selective  oiling' of  the  sulphides.  The  patentees  also  state  that  "a  larf^o 
proportion  of  tlio  mineral  j. resent  rises  to  the  surface  in  the  form  of  a 
froth  or  seum  which  has  derived  its  power  of  flotation  mainly  from  the 
inclusion  of  air-bubbles  introduced  into  the  mass  by  the  a^'itation, 
such  bubbles  or  air-films  adhering,'  only  to  the  mineral  particles  which 
ar.'  coated  with  oleic  acid."  The  la.st  clause  had  bettor  have  bd'n 
omitted,  for  it  is  only  I'on.iecture,  as  to  the  truth  of  which  there  is 
room  i:)r  plenty  of  doubt,  but  the  clear  description  of  air  as  the  main 
agront  of  flotation  is  most  important— far  more  important  as  regards 
the  rationale  of  1h(>  proccs.s,  than  the  diminnti(ui  in  the  proportion  of 
oil. 

As  to  this,  it  is  stated  that  if  ilii'  proportion  of  oil  mentioned  in 
the  previous  Cattormole  patents  "be  considerably  reduced— say  to 
a  fraction  of  1^',  on  the  ore— jrrannlation  coa.s<>s  to  take  ])laco.  and 
after  viporous  a}ritj;ti:)n  there  is  a  tendency  for  a  part  of  tlio  oil- 
eoated  metalliferous  matter  to  rise  to  the  surface  of  the  pulp  ii.  the 
form  of  a  froth  or  scum."    One  per  eent  on, ^  err  is  equal  to  20  lb. 


THE   FUJTATIUX    I'lioCE.^S 


43 


of  (lil  ]>cr  toil;  ii  •fiiictiiiii'  (if  1',  is  iinylliini;  lictweuii  20  iiml  0 
pounds  per  Ion.  In  fiil'oriinf,'  tlii'  ri-ilit  to  the  roHcction  of  royalties, 
the  Minerals  Separation  eoMi|)aiiy  lias  rested  its  claim  mainly  on 
the  reduetiou  of  oil,  (laiminf,'  that  it  produces  a  series  of  piieiiomona 
quite  different  from  any  of  tlie  other  methods  em|)loyinir  lartjer  pro- 
portions of  oil,  and,  concurrently,  insistintr  that  such  superior  effects 
as  are  pro.iui'cd   hy  the  use  of  the  redneid   i|uantity  of  oil  are  un- 

Ifo.  835,120.  PATENTED  NOV.  6,  1906. 

H.  L.  SOLMAN,  H.  T.  KIRKPATRICK-i'ICARD  i  1.  BALLOT, 

ORE  CONCENTRATION. 

ArrLiciTioi  riLCt  utm  itoi 

■  ■■IIT»-4IIIT  I 


\ 


^:^ 


ata^,^*. 


Fro.    12.      THE    CHIEF    MINERALS    SEPARATION    PATENT. 


44 


TiiK  KijirvridN   I'iMCKss 


ohtaiiialtk'  wlicii  \hv  lartrcr  pi-Dpnrtions  of  nil  aic  uscil.  TliiTtii[)(in, 
of  roiu"S(',  it  lias  liii'ii  ilaiini'cl.  Iiy  tliosc  (Irsiiiii^r  to  ijiiiorc  tlic  Minerals 
Sfjmratiori  l)asic  |)atciit,  that  iii'itln'r  the  ('attiTiiiolc  nor  tin'  Froniciit 
iiu'tliodN  ilcrnaiiilnl  a  c|iiiiiitit y  of  oil  notalily  lai'i.'i'i'.  for  the  niiiiiiiia 
pnsi-rilx'd  hy  tlicsr  carlirr  iiivciitors  coini'  under  20  II).  of  oil  per 
ton  of  orr.     Iloui'vri-,  this  matter  is  still  siih  juilicf,  so  it  is  best  let 

alone  for  the  |ireseiit. 

Uetweeii  the  I'roiiient  patent  of  11102  and  the  Sulniaii  I'icard 
Mallot  i)at('iit  of  IIIO")  comes  the  Kirliy  i)atent  V.  S.  Xo.  SOU,!).')!)  of 
1)(  iriiiher  14.  l!to:i.  irranted  on  -laiiuary  Ki.  lIHiti,  This  is  interesting 
as  spceifyinf'  fjentle  a^'itation  and  the  use  of  a  Ka.s,  niakintr  it  possible 
to  use  thin  oils  instead  of  the  viscous  oils  of  the  ])rior  (Klmorc^  art. 
The  claim  is  made  that  "the  injection  of  <ras.  '^■•••fer'd)ly  air.  into  the 
mass,  assists  in  the  flotation  of  the  hydroii.  ..iM-coated  particles." 
The  mention  of  air,  as  an  assistant  flotative  afjcnt,  is  more  important 
than  the  reference  to  the  kind  of  oil. 

The  actual  pai't  jdaycd  hy  the  oil  ha.s  been  misap|)relicndcd  from 
the  very  first,  the  earlier  investijrators  nsinfj  not  eiiou;;!!  to  produce 
bulk-oil  flotation,  while  the  later  mctallurs;ists  have  employed  nnich 
more  than  was  needed  for  bubble  levitation.  Thi^  relative  importance 
of  the  ]iart  played  by  air  wa.s  persistently  ignored  until  a  late  date 
and  evcMi  then  it  was  under-estimated.  It  is  interestini;  to  note  that 
the  two  first  patents  in  which  air  was  specitied  a.s  a  gas  suitable  for 
flotative  effects  were  those  of  F.  Fi.  Elmore  and  the  tirtii  of  Snlman 
&  I'iiard.  l-'raiicis  K.  Klmore  obtaini'd  a  Uritish  patent  for  his 
vacuum-oil  method  under  date  of  August  Ifi.  1004,  and  dui)licated  it 
in  the  I'liitcd  States  as  Xo.  ,S2r).411  of  July  10.  1!»0.").  Sulman  & 
I'icard  obtained  a  Rritisli  patent  for  their  perforated-coil  patent 
under  date  of  Septeudicr  22  lfl03.  duplicating  it  in  tlie  United 
States  as  No.  79:i.S08  of  October  5.  lilO:). 

The  Sulman  tSi:  Picard  patent  .ju.st  mentioned  ha.s  been  claimed  by 
the  Miami  Copper  Company  as  the  one  covering  their  operations  with 
the  Callow  pnenmati<'  cell.-"  In  Xo.  70)5,808  the  inventors  "utilize 
the  ]iower  which  is  ]iosses.sed  by  films  or  bubbles  of  air  or  other  gas 
of  att.iching  themselves  to  solid  j)articles  moistened  by  oil  or  the 
like."  They  also  state  tliat  tliey  add  oil  "in  (piantity  insufficient  to 
laise  the  oiled  mineral  by  virtue  of  the  flotation  power  of  the  oil  alone. 
A  suitable  gas  is  generated  in  or  introduced  into  the  mixture,  such 
na  jiij*  eai'boiHc-ricid  i?.'is.  suliihu ret t ed  h.\*dro!?en  or  the  like  Foi* 
examjile    bicarbonates  or  carbonates,   either  soluble   or  insoluble   in 


sfNote  the  slopinp;  laiin(1pr-lil<e  vessel  iisert  li.v  both.     Sep  Fig.  I.t  and  33. 


IIIK    Kl.iPl  A'l  lilN     IMKM  K» 


45 


Wairr        pl-rhTal.ly     ihr     laltrr       ,,,•    ,,|si|y    .lrr,,||l|MlNali|r    .slll|p||h|.•^    an. I 

til.'  Ilk.'  may  Im'  iis.-.!  ",lh  an,!  s.ijiili.iii. "  'I'lms  th.^y  l.-ss.'ii  tn,. 
.■iiipliasis  .>ii  air  .is  lli.-  |.|iiiii.  atfi'iit.  'i'lir  i|..siTi|ili.>ii  .iImi  ivI'.ts  tn 
111.'  imIi'.I  iiii-taliUVn.us  |.arti.'l.  s  as  ••alta.'liiiitr  \><  lliriiis..|\,-s.  willi 
a  irr.'al.T  .•oiM|iarativi.  si  ri'iii.'t|]  llian  111..  ■_'aiii.'u..  parti. -Irs,  ||i,-  lilms  .ir 


f     873,686  FATENTED  DEC.  10.  1907 

D    H    NORRIS. 

APPARATUS  iilR  ^i  r.ARAIIS.)  THE  MEIALLI  '  PARIICLES  OE  QUi  EKUM 

THE  FOCKT  CONSTITUENTS  THEREOF. 


V 


-/:: 


/■/ 


iO 


tt 


}^dJU 


A 


-/ 


KlG.    i;;.      THE    N0KR1>    I'AlE.vr. 


4« 


TIIK    FLOTATION    I'HOCESS 


lilllililrs  III'  <.MS  whii-h  I'Msl  III  III,'  liiJi.ss  ;in<l  lilf  thus  imimmI  In  llir 
siir!:ir(.    Ill'    Ihc    |i(ii|iir    liy    itjisim.iis    tlntillloii."       Y,\     \\r    ;in'    lohl    that 

tlic    iiii-talliir^'ists    \\ii(i    |>rr|iar((l    iliis    fsnlli  ni    (|i'scfi|)ti.iii    of    the 

lilllililc  Irvilalinll    nirlliud    lliadi'    "a    starllllli,'    (lisrii\r|-\  "    d"    |||r    llnlll- 

iiiir  pfiii-css  fi;.'litrcii  iiiiiiitli.s  latiT.  'I'liis  T.  S.  |palciit  7li.!.>^ns  is  iiinri' 
tliaii  a  y.^ar  .jiiiiini-  In  l-'roiiirnt 's  lliiiish  palnil,  aiiil  i-oiitaiiis  an  c'-Iki 
111'  it   in  llii'  iiil  I'liilui'ldrv  aiinciuiii'ciiicnl. 

Hliinirr's  variiiiiii  nil  jirnriss  inarknl  aimtli'  r  inadvc  rtnit  slcji 
tuwai-ij  till'  ri'i'iiLrnitinn  i>\'  aii-  as  llir  lMo^|  iiiipnilaiit  tlntativc  aL'i'iil. 
lie  iilili/rs  llir  air  iialiirally  <|iss(il\c'(|  in  uatir,  r>li'aNiii'j:  il  Inr  his 
piiiiM.M-  iiiidrr  a  varinini  'I'lic  patent  stairs  that  ••iimlcr  a  variium 
I'l-  partial  \aiuiiiii,  air  nr  t,Ms''s  iIIssciIvimI  in  tlic  milliner  uati-r  arc 
lilirrat.'d.  TlicM'  lilicraird  ^'ascs  may  \ii-  aui.'iiirnt.'d  liy  the  ^'nicration 
i)l'  trascs  ill  llh'  pulp.  Ill-  liy  iiitrndili-lioM  trcnii  an  rxtcriial  sniircr." 
HJiiKiri'  iiivcnti-d  .1  must  iniri'iiiniis  mai'liiin'  t'nr  liis  piirpnsc.  in  so  t'ar 
as  lir  ijipcndrd  ni>nii  tlir  air  in  a  pulp  that  had  inidriL'niir  mixiin,' 
with  a  ipiantily  nl'  oil  I'i'lativfly  small  (as  i'(iiii|)arcd  with  his  hulk  nil 
niithnd  hi-  t'lirnislii'd  a  notahic  nii'talliir'.'ic  sitrii-pnst.  Init  it  is 
nci'cssary  tn  ri'iiH'iiilici'  that  he  iiii\ccl  his  criisliril  nrr  in  aridiilati'd 
uati'r  and  that  the  arid  would  raiisi'  the  frcncriitinn  nl'  i-arhon  ilinxid- 
j;as,  tlnis  ('X[)lainin<,'  his  rrt'crt'iicc  tn  •"air  nr  trascs." 

Thr  lirsl  iiivriitnr  tn  lircak  away  t'rnin  thf  iisn  nf  I'ltlnr  aiid  or  nil 
and  In  maki-  a  idcar  claiiii  for  air  as  his  snlr  Hotativr  a^riiit  is  Diidi.'y 
11.  Nnri'is,  in  !'.  S.  \o.  St;  l.^^oC,  iindrr  date  nf  XoviMiilicr  l!t.  lHf>7, 
alsn  in  Xn.  ST.'!.. ')>;(;.  nf  DcTinlirr  lit.  llt()7.  Scr  Kii:.  l:;.  In  his 
lirst  pati'iit  he  dcscrilicil  a  iiicthod  t'or  "' intrndllriiit;  watrr  cnntaininj; 
air  in  soliitinn  into  the  lower  end  of  an  opcn-fiidrd  rcnptaclc  into 
wliirh  i>.  iiitrmliiiTd  a  tlowiiiLr  mixtiii'r  nf  jiulviT'i/fd  ni'  mixiMJ  with  nil 
and  watrr,  tliri-cliy  cxpnsinsr  saiil  niixtiiri^  to  thr  rontimious  artion  of 
iiifniitesimally  small  na.scnt  liiiMiJcs  of  air."  He  doi's  nnt  spcrify  the 
iisr  of  ai-id  anil  hf  ilistiiirtl>-  says  that  lir  docs  not  wish  it  tn  he  iiiidrr- 
stood  that  his  iiiotliod  "is  limited  to  the  use  of  oil.  as  the  method  can 
he  practised  sueeessfidly  without  iiiixiii",'  oil  with  the  pulvei-izeil  nre 
and  water.'"  Incidentally,  his  iiicthnd  is  worthy  of  friendly  interest, 
for  he  has  dechir'd  his  intcntinn  tn  render  the  use  of  it  free  of  tonnairo 
royalty.* 

Ifaviii'T  got  rid  of  acid  and  nil.  we  have  now  reached  the  i)oint 
whore  modiliefl  water  mi.xcd  with  the  crushod  ore  in  the  presence 
of  air  suffices  tn  form  hiilihtcs  .sutTfieicntlv  lasting  to  huov  th.fl  iMof:!!!!'.' 
particles  to  the  surf.ice  of  the  liquid. 


*Spc  page  274  of  this  tnioli 


TIIK    I  l.olAIION     I'liiiCK.sS 


47 


Tin;  I'.-\(ii<ii.(i.,\.  A  |M.|,.rit  lai'tor  in  ih.-  Iiistuiy  ni'  llotiition  li;is 
Ih.m  thr  |i^yc|io|(,t.'y  nf  iIm'  |).  rsiins  ((iiircrni'd  in  tlir  iiivciitidn,  iini)r()Vf- 
niciit,  mill  appliciilion  of  tli.'  jinHcss  To  uiiilirstaiKl  the  scanty  and 
loiitradirtory  litrnitiir.'  of  tin-  siilijcct  it  is  n.ccssary  to  icad  l.ftwei'ii 
tlir  liii.s  witli  some  knouli'ilirr  of  tli.'  pr|-soiiai  i'i|iiatioiis  that  liave 
r.'n<lcrcd  Ihc  prolihin  ,so  con  liisin^r  to  tiic  la'cr  student.  For  example, 
it  is  an  intcivstins,'  fact  that  the  liisl  uorkalijc  mctho,!  was  that  of  tht! 
KliMoi  >j.  uiio,  however,  siin|dy  carried  forward  the  inetrective  re- 
search of  Kohson  and  Crowder,  at  tin'  (Jiasdir  iiiiiie.  Tiie  Kliiiores 
knew  of  the  experiments  made  hy  IJohwni.  more  particularly,  for 
his   simple   apparatus   was   left    on    view   at   the   mine   when    Francis 

Elmore  and  his  lirother  came  there  in   iMtJ  and  I ame  interested  in 

fh.'  prolilem.  N'cxt  there  is  the  fact  that  in  ]<M)2  the  Hlmores  placeil 
their  Australian  rijrhts  to  the  hulk-oil  process  under  option  to 
the  trroup  headed  hy  Messrs.  Welnster  and  Uallot,  hy  whom  Messrs. 
Siilman  and  I'icard  were  employe,].  The  latter  were  friven  every 
facility  for  hecomiiij;  eom|detely  familiar  with  the  operations  of  the 
KImore  process,  hut  the  Australian  option  wa.s  not  exerci.sed.  and  the 
trroup  that  Iwul  re.jceted  the  option  formed  the  Minerals  Separation 
company  and  proceeded  to  exploit  another  method  themselves.  Where- 
upon, net  unnaturally,  there  arose  charfres  and  couiiter-charKes  of 
had  faith,  jjrovokintr  the  hiw.suit  of  1!t07,"'  which  decided  nothing, 
lait  left  a  lot  of  ill  feelintr  ih  its  wake. 

The  atmosphere  amid  which  the  various  proeesses  were  tried  at 
l^roken  Tlill  is  illustrated  liy  flii>  fact  that  in  the  course  of  a  successful, 
hut  niisleadinfr.  test  of  the  Potter  method,  the  workmen  in  the  Zinc 
Corporal ion'.s  plant  made  it  a  jiractice  to  add  luhricatintr  oil  to  the 
liot-aeid  solution  in  order  to  improve  the  result.  This  fad  was  not 
ascertained  until  .se  ^ral  yeais  d'ter  the  test  had  heen  tinished.  At 
that  time  feeling,  ran  lii<rli  hetween  the  various  procc.s,s  companies  and 
"the  Zinc  Corporation's  experimental  work  was  suh.i'ected  to  many 
unfavorable  arfiruments  of  an  extremely  suhstantial  nature,  .such  as  a 
varied  assortment  of  sT-apiron.  dropped  into  agitators,  gearing,  or 
jnimp  sumps. "" 

In  order  to  understand  the  later  develoi)ments.  it  shnnld  he  stated. 
that  Theodore  J,  Hoover  joined  Minerals  Separation  Ltd.  as  technical 
advi.ser  and  general  mana  er  in  Oetolier  100(5  and  resigned  in  De- 
cember 1910.     rnj)Iea.sant  misunderstandings  ensued.     The  first  edi- 


■•"''Concentratin.!;  Ores  Ity  Flotation."     Pa,i;es  46-48. 

31  n.  P.  Mitchell.    'Flotation  at  Zinc  Corporation,  Ltd.'    E.  .f  M  J    Novem- 
ber 18,  1911. 


48 


THE    FLOTATIUN    I'KUCESS 


tioii  of  Mr.  IIo()ver"s  honk  appcaii'd  i  ,\(i  \('ais  later,  in  Dt'ccmlitT  lltTJ. 
■laiiu-s  .M.  Ilydt'  wa.s  in  the  ciiiplny  nt'  tln'  Mexican  syndicate  organ- 
ized liy  Minerals  Separation  for  one  year,  from  Jaiuiary  llHO  to 
Jainiary  1011.  At  the  instance  of  Herbert  C  Hoover  lie  went  to 
Montana  on  an  inspection  of  the  Butte  &  Superior  mine.  Mr.  Hoover 
withdrew  from  this  business,  but  Mr.  Hyde  proceeded  to  test  the  ore 
anil  erect  a  trial  Hotatioii  plant,  in  tiisrefrard  of  the  Minerals  Sep- 
aration patents.  Suit  was  brought  against  him  by  Minerals  Separa- 
tion in  October  Iftll.  E.  H.  N'utter  was  engaged  by  T.  J.  Hoover  for 
Minerals  Separation  in  litlO;  lie  has  lieeii  in  the  I'nited  States  for 
that  cdiiipanj  since  1911.  most  of  the  time  as  its  representative  in 
San  Francisco. 

•F.  M.  Callow's  American  patent  for  bis  pneumatic  launder  is  No. 
1.104.7.'>''  of  July  21.  Iitl4,  It  covers  the  same  idea  iis  appears  in  T.  .1. 
Hoover's  Hritish  patent  No.  10,029  of  1010.  I  am  informed  that  Mr. 
(allow  was  u!wiwai<'  of  Mr.  Hoover's  invention,  which  was  not  ]>at- 
I'uted  in  fills  count  r\  and  is  now  the  projw'r'v  ,)['  the  Minerals  Se[)- 
aration  company.  However,  priority  of  invention  as  regards  this 
apparatus  is  a  niatt"r  of  acatlemic  inteirst  oidy.  R.  S.  Towne  use<i 
the  same  idea  earlier  than  Mr.  Callow  in  the  form  of  a  carborundum 
wheel,  the  central  hole  of  whi<'h  hi'  plugged,  so  that  the  wheel  served 
as  a  porous  bottom. 

No  American  application  of  the  bubble-levitation  ])ha.se  of  flotati.iu 
to  the  concentration  of  ore  was  made  until  long  after  the  Minerals 
Separation's  ba.sic  patent  had  been  registered.  As  previously  I'elated. 
the  ear'y  trials  were  made  at  Broken  Hill.  Thi'  first  introduction  of 
this  method  in  the  I'nited  States  occurred  six  years  after  the  date  of 
patent  N'o.  s:{,"(.120.  It  is  claimed  l)y  Jlinerals  Separation  that  "if  the 
directions  of  the  patent  are  followed,  the  operation  of  the  process  is 
inevitable."  yet  many  years  of  trial  and  experimentation  were  re- 
(|uireil  1.1  fine  flotation  was  used  successfully  in  this  country.  The 
I'tah  Co]>per  and  the  other  Jackling  companies  made  successful  ai)pli- 
c.ition  of  the  process  by  aid  of  their  own  research  and  persistent  effort. 
Tp  to  1011  the  Minerals  Separation  metallurgists  thought  clialcocite 
could  not  be  treated  by  flotation,  ami  said  so.  In  ^Fr.  Hyde's  report 
of  .January  S.  101 1 .  given  as  an  exhibit  by  Minerals  Separation  i"  t^ieir 
suit  against  Hyde,  it  is  stated  that  the  tests  carried  out  in  tile  com- 
pany's London  laboratory  proved  that  "the  copper  ores  of  a  good 
part  of  the  Southwest  and  also  of  at  least  a  portion  of  the  Utah  region 
contain  clialcocite.  winch  is  not  tiontalile  iiy  any  ot  the  methods  so  far 
tested.''     This  opinion  epitomizes  the  experience  gained   up  to  that 


THE   FLOTATION    PROCESS 


48 


liiiii'  in  llic  Loiidoii  liil"iiiitciiy.  n»,"  '>■:  tlir  ]!tl4  cilitioii  iil  his  Ijook. 
Mr.  Hoovfi-  mentioiis*  the  prcseiicp  of  l)nriiitf  and  i-lialcocitc  as  likely 
to  limit  the  sueeessfiil  operation  of  the  process.  It  is  now  recognized 
that  ehaleoeite  is  easier  to  float  than  pyrite.     It  is  fair  to  add  tliat,  at 


963,746. 


T.  J.  HOOVER. 

mUlTIIB  rOB  ORE  COICEIT&ITIOI. 

irpLiciTioi  THIS  Mil.  r.  isoi. 


Pst«iot«d  Apr  5, 1910. 


'y-n 


I'  U..    H.        lilt.    IHIIIM  K    .Ml'AKM'    -^    r.ML.NT. 


•Page  l!to,      ('oiKentnuinj,'  Ores  liy  Flotatio 


I 


50 


Tin;    FLOTATION    I'KOCK? 


a  later  date,  one  or  two  important  copper  eoinpaiiies  obtained  an  in- 
creased revenue  tlianks  to  tlie  i>isistenpe  of  Minerals  Separation  in 
reeoinmeudinf;^  the  use  of  their  method.  This  insistence  resulted  in 
valuable  eontraets. 

It  is  well  to  warn  the  reader  against  the  inferences  attemi)ted  to  he 
made  from  experiments  in  court,  or  elsewhere,  intended  to  prove  that 
sundry  effects  can  he  obtained  or  cannot  be  obtained  by  following:?  the 
descriiitions  in  various  patents.  As  a  matter  of  fact  the  results  depend 
largely  ujKtn  the  manipulation,  performed  usually  by  an  operator 
who  knows  a  great  deal  that  w<us  not  known  at  the  time  the  description 
was  written.  Moreover,  the  improveiiiert  in  apparatus  enables  a  later- 
day  operator  to  apply  recent  knowledge  in  the  course  of  an  experi- 
ment supposedly  based  upon  an  old  method.  By  aid  of  Ilerodotusr 
and  a  slide  machine  it  is  possible  to  produce  a  performance  that 
might  well  perplex  a  philosopher,  or  a  .iudge. 

In  Mr.  Hoover's  book  the  average  royalty  levied  by  the  process- 
mongers  is  given  as  1  shilling  or  25  cents  per  ton,  Writing  in  July 
11112.  this  author  stated  that  the  combined  capital  of  all  the  com- 
panies controlling  flotation  processes  was  about  $5,000,000.  As  the 
comitanies  had  then  been  in  exi.'tence  for  7  years,  they  should  have 
trcafe.l  .'JS.OOO.OOO  tons  in  order  to  return  their  capital  and  10%  per 
annum.  Up  io  that  time  they  had  treated,  he  says,  only  8.000,000 
tons.  Thus  he  drew  a  melancholy  picture.  But  the  adoption  of  the 
process  by  the  big  copper  mining  companies  in  this  country  is  going 
to  make  those  figures  of  f(.ur  years  ago  look  small  indeed.  This  year 
20.000.000  tons  will  lie  trented  in  !he  I'liited  States  alone;  next  year, 
tiic  tonnage  may  well  increji.se  to  .iO. 000. 000,  taking  no  count  what- 
ever of  the  opcratii)iis  in  Australia.  Chile,  Briti.sh  Columbia,  Korea, 
^Mexico,  and  other  parts  of  the  world.  Soon  it  will  be  100,000  tons 
per  day  in  the  I'liited  States  alone.  Tlie  proc(\ss-mongers  have  a  prize 
worthy  of  a  big  tight  and  the  users  have  an  inc'cntive  to  curl)  any 
a11cmi)t  to  impo.s(>  an  excessive  royalty  acc<nnpanied  by  an  emliargo 
ujion  knowhdgi'.  That  is  where  Minerals  Sei)aration  has  airtagonized 
so  many,  'i'hcy  have  (•lainicd  royalties  where  pr(>\iously  they  had  re- 
porti'd  that  the  ore  was  unsuitable  to  flotation.  Some  of  the  com- 
})anics  that  ai'c  now  operaiiiig  suceessfnlly  went  (irst  to  Minerals 
Sei)aration    for  giiidane,.  and  obtained  so   little  a.s,sisfance  that   thev 


tWho  li;is  tolil  us  .-iboiit   tlie  maidens  ilwplliiif,'  ii|ion  a  ni.vsteiious  islaiui 


on  wh!'.'!i  ihvv 


their  fratliers  in  tlie  iiitcli.  iuiil  flien  iirncpe.led  to  aiiotlief  lake  wlieie  they 
extracted  cold  trciiii  the  sand  liy  Irniliiii;  their  iiiieliy  featliers. 


THE   FLOTATION    PR0CES8 


51 


hiid  to  solve  their  own  ditifioulties  for  thcniselvos.  One  or  two  big 
eonipatiies  iiave  won  reasonal)le  terms;  for  instance,  it  has  been  dis- 
closed that  the  Anaconda  and  Inspiration  companies  have  guaranteed 
that  if  tiie  Supreme  Court  reverses  the  Hyde  case,  or  if  they  do  not 
exercise  tiieir  option  to  surrender  their  license  in  case  of  afitirmance, 
tliey  will  treat  25,000,000  tons  of  ore  by  the  Minerals  Separation 
mctiiod  by  102;},  and  will  pay  the  agreed  royalty  thereon,  this  royalty 
beini?  ji  ciMit  per  pound  of  copper,  but  not  less  than  12  cents  per  ton 
of  ore;  and  meanwhile,  whatever  the  decision  of  the  Supreme  Court, 
they  have  agreed  to  i)ay  a  royalty  of  !f;:J0O.0O0  to  Jlinerals  Separation 
within  a  year  from  date — nine  months  ago.  Having  regard  to  the  fact 
that  the  extraction  by  flotation,  as  compared  with  ordinary  water 
concentration  has  been  improved  from  G.j  to  95%,  at  no  greater  cost 
in  i)lant  or  of  operation,  it  is  obvious  that  the  copper  companies  can 
well  afford  to  pay  such  a  royalty,  if  the  improveiucnt  is  due  to  the 
use  of  patents  owned  by  Slinerals  Separation.  That  point  the  Su- 
preme Court  will  decide  at  an  early  date. 

But.  as  I  have  said,  it  is  not  the  amount  of  the  royalty  but  the 
method  of  levying  tax  and  the  attempt  to  place  an  embargo  on  all 
information  concerning  the  technique  of  the  process  that  has  aroused 
opposition.  The  type  of  contract  made  with  licensees  has  caused 
many  operators  to  refuse  to  come  to  terms;  but  the  more  objection- 
able practice  lia.s  been  the  enforcement  of  binding  contracts  on  the 
metallurgi.sts  employed  by  the  licensees,  such  contracts  being  legally 
invalid  and  representing  an  attempt  to  liluff  the  profes.sion.''^ 

For  the  most  i)art.  until  quite  recently,  the  information  available 
on  the  flotation  proces.s  has  come  from  patentees,  their  friend.s.  and 
their  enemies;  a  good  many  of  the  facts  available  have  been  elicited 
in  the  cours(>  of  litigation,  which  has  now  been  in  progress  for  ten 
years;  tlierefore  a  vast  amount  of  non-science  has  been  mixed  with 
the  little  .science  that  has  survived  amid  thoroughly  uncongenial  .sur- 
roundings. Anybody  familiar  witli  the  bitter  busiii(>s.s  feuds  and  per- 
sonal vendettas  generated  during  the  course  of  quarrels  over  patent 
rights  needs  not  to  be  told  tliat  keen  prejudice,  amounting  in  some 
cases  to  malice,  has  iieen  injected  into  tlie  ragged  literature  of  flota- 
tion. The  \var|>ihg  of  scientidi'  vision  is  astounding  to  the  detachi'd 
observer.  Much  that  has  got  into  print  and  inori'  tiiat  has  escaped  a 
permanent  record  has  been  written  with  a  jaundiced  eye  on  tiie  law- 
courts       On   t(in  of  tlii>;  \)u>   iM,.t:illni-in-  ,^t'  tl...  oi,h;.>,.t   l,..o  I.,,,,..    .^1.,.,.,.I 


•-■Minerals  ;Se|iiiration   Contrarts   with    Mctallursists.'   Miiiinii  and   .s'ric»- 
tiflc  PrrsK.  Feljniar.v  5.  I'Jlfi.    Also  'A  Professional  Matter,'  In  ttie  same  issue. 


52 


THE    KI.OTATION    I'KOCKSS 


miller  an  tiiiliiirfr(»  of  scfircy  liy  the  owiicrs  of  tlif  cliicf  patents,  and 
this  lias  1)0011  oflFootivi  to  the  extont  of  provoiitinp  tlio  technical  men 
in  the  employ  of  the  process-monerers  from  contrihutinp  to  curiciit 
knowledge.  Only  recently  has  there  been  any  considorahle  r.mtrilin- 
tion  from  independent  sources  of  information. 

Another  important  element  in  retarding  the  technology  of  the 
liroce.ss  is  the  ignoring  of  the  fact  that  it  depends  far  more  on  physical 
than  on  chemical  considerations.  To  the  physicist,  not  the  ehemist. 
wc  must  look  for  guidance.  The  metallurgist  hitlierto  has  depended 
ujioii  chemistry  to  guide  him:  he  must  now  go  hack  to  school  and 
ae(|uirc  something  more  than  a  smattering  of  physics,  if  he  expects 
to  understand  the  problems  of  the  new  process.  To  most  of  ur; 
chemistry  conies  more  easily  because  it  has  a  sign  language,  that  of 
the  formula,  to  convey  ideas,  while  physics  depends  ';'~oii  the  use  of 
terms,  half  of  which  bog  the  fiuestion.  Hence  the  stiuu  nt  must  begin 
by  rejeeting  the  use  of  terms  that  !;o  docs  not  understand  and  when 
he  has  learned  to  understand  tiiem  ho  must  take  pains  to  define  them 
Avhencver  he  u:idertakes  to  convoy  his  ideas  to  others.  By  such  sin- 
cerity of  thought  it  will  be  possible  to  make  real  progre.s.s.  and  to 
apply  seienie  to  industry  with  results  far  Iranseeiiding  any  hitherto 
achicvod  in  this  field  of  human  activity. 


KI.(JT.VTI0.V  TESTS  AT  MOINT  MUK(JA\ 


'>:\ , 


FLOTATION  TESTS   AT   MOUNT   MORGAN 

By  William  ^roTiiER\VEi-L 

(  (•"roiii  tlif  MniMi'i  and  Scieiitific  Prrs.s  of  June  27,  I'JU) 

The  .Aloiiiit  Morgan  gold  mine  in  Queensland,  Au.stralia.  which 
was  disi-oveivd  alioiit  ISO  years  ajjo,  is  Relieved  to  he  the  richest 
indivitlnal  gold  mine  ever  found,  having  produced  over  $70,000,000 
worth  oi  gold  to  date,  besides  copper.  In  its  early  stage,  the  ore, 
which  carried  hundreds  of  ounces  to  the  ton,  was  cnislied  with 
stamps  and  amalgamated,  but  the  recovery  was  not  especially  good. 
Subsequently,  and  until  seven  years  ago.  all  the  ore  was  dry-crushed 
in  ))all-mills,  roa.stcd.  and  leached  with  chlorine  solution  in  open 
lirick  vats  and  the  gold  precipitated  on  charcoal.  At  that  time  the 
copper  content  of  the  ore  was  negligible.  This  is  our  of  the  few 
large  gold  mines  in  the  world  that  never  had  a  cyanide  plant. 

About  eight  years  ago,  a  large  body  of  rather  silicious  cupriferous 
sulphide  ore  was  found  in  the  mine.  Blast-funiaces  were  erected, 
and  the  less  silicious  ore,  which  contained  about  $10  gold,  -1% 
capper,  and  45%  silica,  was,  and  still  is.  being  smelted.  The  more 
silicious  or  so-called  'mundic'  ore,  carr>-ing  about  $15  gold  and  1% 
copper,  was  then  dry-crushed,  roasted,  leached  with  sulphuric  acid, 
the  copper  being  precipitated  on  scrap-iron,  subsequently  l-^ached  in 
the  same  vats  with  chlorine  solution,  and  gold  precipitated  as  before 
mentioned.  About  1«  im)nths  ago  the  gold  content  of  this  'mundic' 
ore  began  to  decrease,  and  the  copper  content  to  increase.  For  this 
and  other  reasons  it  was  deemed  advisable  to  cease  this  method  of 
treatment,  and  the  last  of  the  chlorination  works  was  shut  down. 

It  now  b.caiiie  necessary  to  tind  a  protitaMe  method  of  handling 
this  cla.ss  of  ore.  As  iron-bearing  flux  has  to  be  brought  a  long 
distance,  and  as  the  ore  carries  about  70%  of  insoluble,  smelting 
would  be  too  expensive.  Tliere  is  believed  to  be  at  lea.st  2,.")00.000 
tons*  of  this  cla.ss  of  ore  in  the  miiir.  a.ssaying  roughly  $0  gold  and 
2%  copper.  This  is  in  addition  to  th.>  so-call.d  'copper  ore'  which 
is  l>eing  smelted.  It  may  be  explained  that  there  is  no  'carbonate 
zone'  in  this  mine.  All  the  copper  is  in  the  form  of  chalcopyrite. 
The  gdbl  is  verv'  fine. 


A    few  years  ago   some  experiments  were   made   by  (Tushing   in 


•Thf  long  ton,  2240  lb.,  is  used  throughout  this  article. 


54 


THE    Fr.oTATION    I'liOCKSS 


ball-iiiills  and  uoiu'fiiti-Mtin^'  cm  WilHcy  tal)lis,  hut  they  wcru  not 
succcssriil.  [,a.st  year  it  \v;is  tliMidcil  tii  make  a  tliorou^'li  trial  of 
the  .Minerals  Separation  imness.  and  a  small  testing  plant  was  ereeted 
in  tile  lalioratory.  At  the  same  time  a  full-sized  experimental  unit, 
ca[>alile  of  treatinfj  :{()()  to  4(l()  tons  jter  24  hours,  was  ere<ted  in 
one  of  the  abandoned  ehlorination  plants.  Hotli  sets  of  experiments 
were  carrieil  out  by  the  nietallurtrieal  statT  of  llie  ('om[>any.  After 
they  were  finished,  a  representative  of  the  Australian  braneb  of 
Minerals  Separation.  Ltd.,  paid  a  visit  to  the  nune  and  eondueted 
a  few  tests,  wliieh  eonfirmed  the  results  olitained  by  the  mine  stafT. 

As  mentioned  in  the  Company's  annual  ie|)ort,  thes(>  tlolation 
experiments  were  sueeessful.  the  extraetinn  lieinfr  hifrher  and  the 
costs  lower  than  expect(>d.  The  company  is  now  buildinj,'  the  first 
unit  of  a  plant  to  treat  1000  tons  per  L'4  hours.  The  ore  will  be 
cru.shed  by  roek-breakers.  Symons  disc  erushers.  rolls,  and  tube-mills. 
It  will  thi-n  be  eoneentrated  on  Wiltley  tabb's.  after  which  it  will 
po  throutrh  a  second  set  of  tube-mills,  thence  to  the  flotation  machines. 
It  is  i)resuiiied  that  no  royalty  will  be  payable  on  the  ^Vilfley 
coni-ciili-ate.  This  concentrate  will  eitlni-  be  bri(|nettc(i  or  sintered 
in  a  Dwiprht-Lloyd  machine,  and  smelted  in  blast-furnaees  alonj;  with 
the  'I'opper  ore'  and  ii-onstonc  and  limestone  fluxes.  The  Compan.v 
has  no  reverberatinnr  fnrnnces. 

Al'I'l.If ATIii.V    OF   Fl.dT ATId.V   Til   (iol.I)   (tUK 

A  flotation  i)lant  is  bein<r  erected  at  the  Falcon  mine.  Khodcsia. 
to  tnat  on-  eontaiiun^'  pild  and  cojiper.  With  the  exception  of  the 
]\It.  :Morjran.  tlit  Etheridf,'e.  and  the  (Ireat  Fitzroy  mines.  Queensland, 
I  have  not  heard  of  the  flotation  i)roeess  b(>in(j  u.sed  suci'cssfnily  to 
treat  ore  containintr  an  ajipieeialile  anmunt  of  frold.  The  KImore 
♦  hick  oil  i)rocess  was  installed  at  the  Lake  View  Consols  trold  mine, 
Kaljiroorlie.  .several  years  ajro.  but  was  not  successful,  as  the  ore 
was  not  suitable,  and  unsuccessful  experiments  wei-e  made  by  Minerals 
Separation.  Ltd..  on  ore  from  the  Lancetield  nunc.  Western  Australia, 
which  contains  mispicke].  The  Elmore  vacuum  i)ro.'ess  was  installed 
at  the  Cobar  iSn\,\  mines,  Xew  South  Wales,  and  at  the  New  Havens- 
wood  ^'old  mines.  Queensland.  I'.otli  these  mines  contain  coi)per  in 
the  form  of  sulphide.  ,-is  v. '11  as  f.'old.  but  tiie  plants  only  ran  a  few 
Weeks.  I  was  informed  thai  the  pbiiit  at  the  former  mine  (where 
iiie  (Uf  ciiiiiaiiis  aiiipui  .>S  truid  ami  "[.■■  ,  cojiper  ^  ^avi'  a  fair  recovery 
of  co])|K'r.  but  left  too  much  irold  in  the  tailin<r  or  left  enough 
copper  in  the  tailing  to  prevent  profitable  cya?iidalion  of  the  gold. 


FLOTATION  TKSTS  AT  MOINT  .\I(m(iAN 


55 


T(i  rctiirii  to  tlic  .Mt.  .Mdrjraii  iiiinc.  the  laluiratory  jiijparatus 
liail  a  capacity  of  one  pound  of  ore  at  a  time,  and  tiic  rcsidts  now 
In-intr  olitaiiicd  in  tii.>  c\i)criincn1al  mill  api)roxiiiiatc  clost'ly  those 
obtained  in  the  hilioratory.  The  ol).iect  of  concentration  was,  of 
course,  to  obtain  a  concentrate  containing  as  much  gohl,  copper, 
and  iron,  and  a.s  little  silica  ns  ])ossible.  coirniiensurate  witli  a  pood 
extraction  of  the  f,'nl,l.  b.vaiis.-  it  was  found  that  the  less  silica  the 
concentrate  contained  the  poorer  was  the  extraction  of  pold.  It 
costs  l.i  cents  to  flux  one  unit  of  silica,  and  it  was  neces.sary  to  steer 
a  middle  course.  Kxperiinents  ma(h-  with  Sonstadt  solution  on  ore 
from  one  part  of  the  mine  showed  that  clean  quartz  (after  separation 
by  si)ecifl(  srravity  from  all  mineral >  c()ntaine<l  not  lc.s.s  than  sfil.oO 
trold  per  ton.  In  practice,  of  course,  it  is  impossible  to  float  all 
the  mineral  and  sink  all  the  ganpue. 

The  asitator   in   the   lal>onitory   plant  was  at   first   run   at   1100 
r.p.m..   l)ut    was  afterward   reduced   to  800.      Tests  were   made   with 
I>ulj)s  of  different  proportions,  each  separate  pulp  being  agitated  for 
the  .same  length  of  time,  that   is,  (i  minutes,  and  it  was  found  that 
there  was  not  nnich  difference,  in  the  extraction  of  gold  and  copper, 
between  a  pidp  containing  three  parts  solution  to  one  of  ore,   and 
a   ])ulp   containing  seven   i)arts  solution   to  oni-   of  ore.      A   pulp  of 
1  to  1  was  too  thick  and  gave  poor  results.     In  practice,  the  thinner 
the  pulp  the  smaller  the  capacity  of  the  flotation   machine.     Tests 
wc^re    also    )nade    to    a.scertain    the    effect    of   agitating    for   different 
lengths  of  time.     Two  tests  were  made  in  the  laboratory  of  which 
I    have  a  note:  one   for  10  mitnites  and  one   for  1.')  minutes.     The 
ore  contained  .^0.50  gold  and  2^,'   .'opper :  12^,'   of  this  .sample  would 
remain    on    a    (iO-mesh    .screen.      The    first   one    gave    a   concentrate 
containing  $22.70.  t).4f-,'   copper,  and  18^;   insoluble,  with  an  extrac- 
tion of  51';;    of  the  gold  and  84.5^;    of  copper.     The  second  gave  a 
concentrate  containing  .■i<20.20  gold.  7.8' ;   copper.  ;ind  27','    insoluble, 
with  an  extraction  of  04..")'-;    of  ir„]d  and  01  S^;    copper.     The  gold 
left  in  the  tailing  was  probably  in  the  gangii.  .  as  the  extraction  was 
poorer  than  usual.     As  a  rule,  the  longer  agitation  and  separation 
are   continued,   the   more   silicions   the   concentrate   is.      In    practice, 
the  length  of  treatment  is  regulated   by  the   thickness  of  pulp   and 
the  number  of  boxes  in  the  flotation  ma<-liine.     Tests  made  to  ascer- 
tain to  what  degree  tine  cnishing  was  necessary  .showed  emphatically 
iiiai   iiic  ore  nuist  aii  pa.ss  tiirougli  a  scrci-n  of  (id  jioles  to  the  linear 
inch    if  a   good   extraction   is   to  lie  obtained,   and   that    the   finer  it 
was  crushed,  nt  any  rate  down  to  120-mesh.  the  better  the  extraction 


'^'' 


56 


TlIK    I'l.OTA'ridN    I'ltoCKSS 


\v;t.s.  Tests  sliDWi'il  lliat  uiicii  usiiii;  I'Ucalyptus  nil  tlifi'i-  \\a.s  H'l 
advaiitnjie  in  iisin^  iiii  aciil  soliilidii.  Init  tliat,  on  tlic  otlin-  liand. 
slifjlit  acidity  did  no  liariii.  Miicii  of  tlic  co|»[)i'i'  |>yrite  in  the  ori> 
readily  floats  on  water  witliout  any  |)re\ious  ajiilation.  On  treating 
ore  contaiiuiifj  $1'.")  trold  direct  liy  a!.'itation  ancl  tlotalion.  without 
anifdgainating  or  concentratinK  on  tables,  it  was  ])roved  that  fine 
free  gold  can  lie  Hoated  liy  usinir  eucalyptus  oil. 

r<K  OF  H>si;nti\i.  Oh.s 

-Many  oils  were  teste<l.  and,  jrenerally  s|)oakiu}j:.  it  was  found 
that  only  essential  oils  gave  a  coherent  froth  and  good  extraction, 
other  oils  like  i)etrolenin.  oleic  acid,  and  lubricating  oils  tending 
to  form  granules  which  sank.  The  best  residts  were  obtained  from 
eucalyipfus.  (dosely  followed  by  Essential  ("  and  Pinus-  Imirxs 
riilf/iiris.  Oleic  acid,  wliicii  was  used  for  years  at  Broken  Tlill  on 
zinc  ore  with  hot  solution,  and  gave  good  residts  when  tried  on  this 
ore  with  neutral  and  acid  solutions,  gave  an  enormous  froth  and 
floated  most  of  the  siliea.  .\  mixttirc  containing  '.)'t'~',i  of  eucalyptus 
and  oidy  ")'~;  of  oIimc  acid  gave  a  concentrate  containing  47'7e  silica, 
showing  the  power  of  the  oleic  to  float  silica.  E.xperiments  were 
after'vard  m.ide  with  a  mixture  of  oils,  and  one  eondnnation  (known 
as  Mt.  ^lorgan  mixture)  \>as  fo;ind  to  give  a  better  extraction  of 
both  gold  and  eoi>per  than  any  of  the  individual  oils,  and  at  less 
expense.  When  the  samjtle  was  all  cnislied  to  pass  SO  mesh,  an 
extraction  of  80^  of  tlie  gold  and  !)0^r  of  the  co]iper  coidd  be 
ol)tained  every  time,  with  a  concentrate  containing  about  2n% 
insoluble,  which  can  be  reduced  to  10%  hy  re-treatment.  Hot  solu- 
tions an<l  a  solution  containing  1'",  of  common  salt  wei-e  found  to 
lie  detrimental  to  good  recoveries. 

Recovkuy   by    Fi.ot.vtio.v 

A  test  on  a  sample,  ci'uslied  to  pass  a  .screen  of  120  holes  pt>r 
linear  inch,  containing  $:!7  gold  and  4.8%  copper,  gave  a  recovery 
liy  flotation  alone  of  OO^c  of  the  gold  and  !)8.r)%i  of  the  copper,  but 
left  ."iiS  gold  in  the  tailing.  The  concentrate  carried  44%)  in.soluble 
matter,  which  could  l)e  reduced  by  re-treatment.  A  different  oil 
( eucalyptus!  would  have  given  a  poorer  recovery  and  a  cleaner 
concentrate. 

Tests  made  on  ore  containing  $9  gold,  3.5%  copper,  and  45% 
insoluble,  showed  that  after  crushing  to  pass  60  mesh  and  treating 
bv  direct   flotation,  an   extraction  of  82'~;    of  the  gold  and  Wy'",    of 


I'l.oTATlUN  TL^-'IS  W  MKIN  T  MdKii  \N 


57 


i 


llif  (-(ipptr  iMinlil  111'  ol.taiiiiii,  witli  a  (•(.iicciilratu  udiitaiiiiii!,'  uiily  L'l', 
iiiMilulilr.  N,)  (l.iiilit  with  liiiiT  cnisliiii!,'  t'Vfii  lii'ttiT  recoverii-s  would 
lie  liail.  Tlicsc  results  Iravi-  fabl.'s  and  vanncrs  far  hehiiid.  It  was 
found  decidtHily  advantageous  to  re-use  the  solutions. 

A  Wilticy  talilf  was  tTccti'd  in  llic  mill,  some  tests  made,  and 
the  tailing  treated  jpy  Hotation  in  the  laboratory.  Sometimes  these 
tailintr  .samples  were  dried  before  flotation,  and  sometimes  they  were 
not.  It  was  invariably  found  tiiat  a  better  e.\tra''tion  was  obtained 
from  those  whieb  had  not  been  dried,  as  no  matter  how  carefully 
the  operation  wa«  conducted,  some  of  the  iron  pyrite  got  suliliciently 
o.xidized  to  resist  flotation,  and  it  carried  some  of  the  gold. 

In  some  of  the  tests  the  crushed  ore  was  concentrated  by  paruiing 
in  the  laboratory,  and  afterward  subjected  to  flotation.  In  this  case 
the  water  in  the  laboratory  was  used,  which  did  not  com.'  from  the 
same  source  as  the  water  used  in  the  mill.  It  was  noticed  that  the 
longer  the  .siimple  was  allowed  to  remain  in  the  water  after  panning, 
the  worse  the  subsequent  flotation  was.  For  example,  where  flotation 
took  place  immediately  after  vanning,  the  residue  assayed  .'i;2.G0  gold 
and  0..'5(K;;  copper,  but  where  tailing  from  panning  was  allowed  to 
remain  under  water  for  6  hours  before  flotation,  the  residue  assayed 
$3.10  gold  and  0,67%  copper.  .\n  analysis  of  this  water  was  made, 
and  this  incident  shows  what  might  happen  in  a  mill  where  the  ore 
is  in  ccntact  with  bad  water  for  .some  hours  before  reaching  the 
flotation  machine,  sueli  as  the  time  it  is  going  through  rolls,  Chi!(>an 
mills,  tube-mills,  and  ela.ssitiers.  over  tables  and  through  thickening 
devices,  and  perhaps  through  secondary  tube-mills.  The  water  in 
question  was  neutral,  botli  before  and  after  coming  in  contact  with 
the  ore. 

Some  tests  were  made  both  in  mill  and  laboratory  in  which 
fiir  was  drawn  into  the  agitation  bo.xes  through  pipes  fixed  vertically 
in  the  corner  with  the  top  open  to  the  air  and  the  bottom  ending 
in  a  lieiit  pipe  terminating  under  the  impeller  of  the  agitator.  No 
improvement  was.  however,  noticeable. 

Grading  tests  were  conducted  on  crude  ore  and  flotation  iiroduels. 
Tlitv  showed  that  a.s  regards  crude  ore.  after  crushing  either  in  mill 
.ir  laboratory,  the  finest  grade  of  concentrate  or  nre  was  the  richest 
and  the  coarsest  grade  of  tailing  was  ricln  st.  both  in  gold  and  copper. 
The  fact  that  the  finest  grade  of  tailing  was  the  poorest  shows  that 
tiiis  prore.s.^;  uiii  noar  the  iiiiesi  suipiudes  suei'essfuliy. 

rRl'SHING    Pli.\NT 

In  the  experimental  mill  the  ore  is  crushed  m  rock-breakers  and 


58 


Tin;  ri.uT\ri(iN   ruocKss 


Kni])i)  (li'ViTUsliiii!^'  Iiiill-iiiills  witlmut  dniiij.'.  'I'lii'^  plant  was 
I'oriiifrly  iisnl  in  mish  uxidi/iil  <in'  lni-  chldiiiiatinii  and,  luinjx  "n 
llu'  spot,  il  was  naturally  utili/rd  in  |)rct\  rcnrc  lo  hiiyinj,'  iirw 
inar|iiiic|-y.  'I'll.'  i-i'iislicd  nir  dnips  into  a  Inn  at  tlu'  liottiini  of 
which  aiT  two  ('hallciisrc  Vndffs.  Thi'sc  deliver  the  ore  into  a 
laiiiidcr  when'  it  is  met  hy  a  stnam  of  watn-  whiih  carries  it  direct 
to  a  six-coiiipartiiient  Minerals  Separation  machine.  Haeh  spindle 
is  driven  hy  a  half-crossed  licit,  thus  eliiiiinatins,'  the  noise  and  i^reaso 
incidental  to  the  old  IJroken  Hill  method  of  pearins;.  The  machine 
is  of  the  Hoover  single  level  type,  hy  which  one  man  can  attiMid  to 
all  the  flotation  hoxcs.  The  concentrate  was  collecteil  at  first  in 
c'ireular  wooden  vats  with  filter-bottoms  of  cocoa  inattinp.  and  later 
in  shallow  rectanirular  eonerete  taid<s  which  formed  ])art  of  the  old 
ohlorination  works.  The  whole  i)lant  is  extremely  siiiii)le  and 
reipiires  very  few  men  to  run  it.  It  has  not  l»een  found  practicable 
to  use  a  screen  finer  tlian  Mo  mesli  on  tlio  hall-mills.  It  is  fotnui 
that  the  gold,  copper,  and  iron  contents  are  preafer  in  the  eoneen- 
frate  overflowing  from  \o.  1  box  and  that  they  pradiially  decrea.se 
until  No.  6  is  reached,  while  the  siliea  I'ontent  increases  from  10';; 
in  the  concentrate  from  \o.  1  box  to  altout  oO'^;  in  that  from  No.  6. 
About   ")()  hp.   is  rccpiired   lo  drive  the  a<ri1ators  at  IJ'jO  revolutions 

per  minute. 

As  it  is  intended  to  use  Wiltley  tables  in  the  new  mill  to  assist 
in  reeoverinw  the  iron  j)yrite  in  the  ore  for  tluxinp  aiul  other 
purposes,  two  of  these  machines  were  placed  in  the  experimental 
mill  and  some  tests  made  to  find  <mt  wliat  residts  may  be  exin-cted 
of  them.  Takincr  an  average  of  several  tests  on  ore  from  ditTerent 
l)arts  of  the  mine,  the  pradinp  of  the  'table  feed'  was  as  follows: 
10%  remained  on  60  mesh,  and  19%  passed  through  60  but  renutined 
on  120  mesh.  It  contained  it^-t.iiO  rrold.  1.80'  copper,  0%  iron,  and 
76%  insoluble.  The  concentrate  assiiyed  $17  pold.  2.9";;  copper,  34% 
iron,  and  18%  insoluble;  tlie  recoveries  were  :i.']':;  of  the  pold,  H!';;  of 
the  copper,  and  38%  of  the  iron.  No  doubt,  had  the  pulp  been 
I'bissified  and  the  fine  material  passed  over  slime  tables  or  vanners. 
better  res\ilts  wo\dd  have  been  obtained,  but  the  Company  does  not 
intend  to  use  mechanical  concentrators  for  the  slime,  prcferrintr  to 
rely  on  the  flotation  process,  so  it  was  not  worth  while  experimenting 

n-;»li     til  mil 


Durinsr  the  flotation  experiments  with  eucalyptus  oils  some  tailing 
was  produced  which  contained  a  fair  amount  of  gold,  and  atfempts 
were  made  to  recover  some  of  this  by  amalgamating  and  cyaniding. 


I 


FLOTATION  TESTS  AT  MOfNT  M()K(i  VV 


59 


It  uas  tdiiiid  that  \ut  cxtrartion  liy  a.iialu'aiiialinn  was  iKissihlc.  n  !• 
was  any  I'xtrai'lioii  l)y  cyaiiidiii^  [Missihlc  witlioiit  I'itlicr  masting 
or  tiniT  ^,'rindinf?.  On  iinroiustfd  tailing?  ussaying  sfif  K»1<1  "iid  (',4K,' 
copprr,  after  crusliintr  t"  pass  120  niesli,  soparatinj?  the  slinu'.  and 
Icacliiiif?  the  sand  for  !t  days,  an  rxtraction  of  only  tJOi*.  p 'r  ton 
was  olitaiiicd  with  a  consiiniption  of  :j.(j  Ih.  of  cyanide  per  ton. 
On  a  ditVcicnt,  tiiijiiitr  <nishfd  to  psuss  80  mesh,  wliieh  after  slime 
was  separated  ius.sayed  y^'2.'.M  fjoM  and  O.liO','  copper,  an  extraction 
of  $1  was  ohtained  in  ,'>  days  with  a  consumption  of  2  II).  of  cyimide. 
Samples  of  slime  were  treated  l)y  atritation  and  washed  l)y 
doeantation,  and  pave  sli^/.itly  better  extractions,  hut  tiie  cons  imp- 
tion  of  cyanide  went  up  to  (J  or  7  Ih.  The  strensrth  of  solution 
used  in  these  tests  was  OAO'',  KCX.  It  should  perhaps  he  noted 
that  all  samples  of  flotation  tailini,'  had  heen  dried  hefore  heiii>? 
tested  by  eyanidaf  ion. 

KkFKCT    OP     HOASTINli 

Two  samples  of  sand  from  tailing  were  roasted  and  treated  by 
percolation.  The  value  was  $:i.  The  roasting  reduced  the  sulphur 
to  0.5%.  Although  the  copper  and  iron  were  oxidized  by  roasting, 
the  eonsui'iption  of  KCX  was  less  than  in  treating  the  unroasted 
tailing,  which  was  contrary  to  expectation.  With  three  days  treat- 
ment, the  residue  was  reduced  to  $1  per  ton,  and  about  one-third 
pound  of  copper  was  dissolved  from  each  ton  of  tailing  by  the 
cyanide.  The  consumption  of  cyanide  was  1.4  lb.  per  ton,  so  that 
the  extraction  was  Insrher  and  the  loss  of  cyanide  less  than  in 
treating  unroasted  tailing.  Speaking  from  memory,  I  think  that 
attempts  to  regenerate  the  cyanide  in  solution  by  means  of  sulphuric 
acid  and  lime  were  not  very  successful.  The  sf)lution  contained  0,05 
gram  copper  per  litre. 

These  c.vaniding  tests  were  mert^ly  done  for  information,  as  it 
is  not  exjiectcd  that  the  tailing  from  tii  new  mill  will  be  profitable 
for  cyaniding.  The  subject  of  extracting  gold  from  flot.ition  tailing 
arose  a  few  years  ago  at  the  C'obar  gold  mines,  as  already  mentioned, 
but  in  Ihal  caw  (he  diniculty  was  overcome  by  selling  the  mine, 
which  contained  highly  silicious  ore.  to  a  company  which  owned  a 
.smelter,  and  had,  or  thouglit  it  had,  plenty  of  basic  ore  for  flux. 
T'nfortunatel.v,  the  amount  had  beeti  overestimated  and  the  problem 
IS  sliii  uii.soiveii — o'lit  tiirti  is  anotncT  Siory. 


eo 


THE   FLOTATION    PROCESS 


OILS  USED  IN  THE  FLOTATION  PROCESS 

Uy  An  OccA^iuNAi,  ('(induui  iciu 

I  I'loiii   llii'   Miiiiicj  iin'i  Sfiiiitifii    I'liss  ol    May    1.   i;il.')i 
I     I  i,'i  iiM  I  iiiin  .     Tlir  «iirkip|'  lit.    |)ii.st   twii  _\  I  iirs  ill   iii,iii>    mill-  iii 

tlir     1    rillcil     Slillo.     Mi'M.Mi.     ;i||i|     S.illlh     A  IIH'l  iiM .     llilS    lliili.-     .iiiiili     In 

|ini\r  llii-  siiitali:lit  \  I'l  tlotati'Ui  iirnn^scs  tn  tjn'  riToviTv  "I  tlir  miI 
|i|ii(|i'  (•r(>  ol'  ciipiiiT.  iiinl  III  iiiilii'ali'  till'  lirsi  iTaL'rnls,  In  a  irriitral 
way.   It   iiiav   lie  (anl  llial  uiIn  ol'  luiiural  iiri|.'iii,  m|i-Ii  as  mal  tar  ami 

I'llrl  ml.   i,'l\r    lirtlrl-   M'-UJK  (ill    rnllli.T  ofcs.    wllill'   nils   (iT   \i  '_''  lal    nli'-'ill, 
SUi-ll   as  till'   ti'l'lirlh  s.    |iih''ncs,    WimmI  tars,   cti'.,    arr    iirttrr    ,ii|a|ili'.|    for 

tln'  troi!tiin-n1  dt'  /iur  ami  liad  oit's. 

(''i\i..T\K  I'liui)!  I  r-.  Aiiioiiir  tlirsr  cri'sylir  and  cai'lmli'  ai-ids  are 
tlif  lirsi  kiiiiwn  ri'ai;<'iits.  ( '(uiiiiH'rcial  crcs.vlic  acid  is  an  nily  rrl'rac- 
livr  liijiiid.  jTriiirally  with  a  ml  nr  y-'llow  lin^'i',  lias  a  s|irciiif  L'ra\ity 
III'  aliiiu';  l.(i44.  and  nmsists  i>\'  a|iiiriixiiiiatcly  4"',  nn'tai-rcsylir.  .!.")',' 
cii-tliiii-ri's.\  111',  and  -'>'',  ]iarai-i'rsylir  arids,  the  pnipcrtirs  nt'  tlioso 
tluvf  isiiiiiers  lii'intr,  ai-rmilinix  tn  Lunsrc  and  Kraiif:' 

Solubility  in  100 

parts  water,  ordl- 

Acii!.  R  1'.  nary  tcni|ieratiire. 

Orthocrfsyli,    IHI '  2.J0  vol. 

Metacresvlii     20;; '  0.3?,      • 

I'ar.icn-s-lir 2ii2'  l.SO     " 

'I'liis  ai-iil  is  iiiurli  Irss  snlulilr  in  wati'i'  than  its  hmunlnunr.  lai'lmlit; 
arid,  and  is  still  iimrr  rasily  lirnkrn  ilnwu  hy  siiliiliurir.  whirii  iirnlialil.\' 
ai-i'i>unts  fnr  the  stidriiinit  that  siilphnrir  arid  may  not  he  iisid  almii; 
with  t'ithi'i  lit'  these  weaker  aeids.  .My  own  exj)eriiiieiit.s  trivi'  i  onriiet- 
iiitr  results   ,ind  I  (  aiinot  sjieak  with  rniilidenee  on  this  point. 

1  liavi-  |o\iiiil  a  marked  dit1'ei-enee  in  the  liehavior  nl'  diil'ereiit 
lirands  oT  eresylie  aeid,  and  I  siiLrirest  that,  in  eonjiii-.etinn  with  test.s 
run.  the  dilVereiit  ln-aiiiU  he  aiialx/ed  to  see  what  liearine  the  ditl'er- 
in^  aiumint  of  the  three  ennstitiieuts  has  on  the  action  of  the  various 
aeids  I  had  vei'y  pnni'  siieeess  ill  treatiiij;  a  eertain  e'.iale.ieite  ore  with 
a  dark  enlnreil  eresylie  aeid.  and  on  eliani.'inir  over  to  a  liL'li!  'iiliiii.,! 
Iirand.  I  had  itiiiiiediately  suri)risin<_'ly  trood  I'esults. 

LuiiL;e  and  Keane  fjive  a  method  ("  Iiaselie<x"s  for  the  i^st  imal  inn  if 
the  three  isomers  of  <'resylie  aeid.  For  the  lieiletit  of  tlmse  wh.i  mav 
not  have  aeeess  to  this  hook.  I  jrive  it  in  full  ; 

1  Tiiliiiiial  Melhoils  nl'  Cheniiial  .Viialysis.'  tlill. 


OILS  l>Kli  IN    ^M^.  1  IDIKTIIIN   I  l(()(h>S 


»;i 


<  >M     iKJllill^'    //I    1  IT.SIll     Willi     i\rr>,S    clI      IINO    .    ill      I'MI       ll     l^    .|llillll|lM 

ti\cl>  (Diivcrtcil  iiitii  triiiilriKTiMpl.  wliilc  if-,  iMimcis  mr  >  m-miIi  triy 
oxidi/i'd  to  OAalii;  aciii.  Tlif  'nllowinj;  ilirt'ctiiniN,  wliirli  must  lie 
iiiiist  .urcl'iilly  (ilisiTvi'd,  y,i\r  rrlialili'  I'fsiilts;  Mxa'ily  In  v'i';iiuiii>'s 
el'  I  111-  (  tcndI  iiiixtuii'  ;iir  Wciirlird  iato  ii  siii.ill  cunii-al  fl;i.sk  mixed  with 
1')  (■.,■  iirdiiiaiy  ll^S(),  il.N4  ,  then  ticatcd  tor  1  lidiir  m  a  stiaiii 
(i\(ii.  and  the  ((Piit-'iits  |)oiirtd  into  a  w  idc-iiickid  Hask  "I'  1  litVf 
(•a|iai-ity.  'I'hc  tlask  is  ciHili'd  iiihIit  tlif  laji,  sliakiiiir  it  I'nuiid  mean 
vvliilc  in  siii'li  a  inanner  tiiat  tlic  siilplionii'  a<'ic|.  wlii(di  is  a  nmliilr 
li(liiid  w  iiilc  lint,  settles  as  a  tliiuk  Nvnip  un  the  sides  nl'  liie  Hask  diii'iiitr 

eiHijlllir.      'H»  e.".   dl'    IIN'O      il.!!N'    ai'i'   tlieri    ti|-st    |i(ilireil    into   tile   small 

tlask  ill  wliieli  tile  siil|p|ioiiatinii  was  rniidiic-ted.  in  urder  tn  I'eiimve 
any  siil|ilmiiie  arid  adliermi;  tu  iis  sides,  i'  ,ed  well  niiind,  and  tlieii 
jinured.  all  at  miei',  into  tlie  lartrer  tla.sk.  The  ennleiits  nt'  the  lailer 
are  Well  shaken  iiiiiiiediately.  so  that  all  the  sulphonie  acid  is  dis- 
s(p|\i'd.  wlii"li  takes  ahullt  iJn  seemids.  The  tlask  is  then  plaied  in  ii 
draiitrlit  eu|)lM>artl.  After  one  ininiitf  a  violent  reaction  occuis.  it'.l 
I'llliies  are  evolved,  and  the  li(illid  hoils:  then  it  suddenly  liecomes 
tiirliid;  oily  dro|)s  ot'  trinitroeresol  I'oi'iii  and  eolii-t  on  the  liottom 
lit'  the  Hask  ;  and  alter  five  iiiimites  tli.  rea'tion  is  appareiitlv  ended. 
The  whole  is  allowed  to  stand  for  at  least  another  ti\e  ininiites.  then 
poured  into  a  dish  eontainiii^'  4n  c.e.  water  and  llie  tlask  rinsed  out 
with  a  further  40  e.c.  water  into  the  same  dish.  On  luixintr  wiiU  water 
the  trii.it ro-//i-cresol  solidilies  with  liheration  of  nitrous  fumes  to  a 
crystalline  ma^xma.  It  is  allowed  to  stand  for  at  least  two  hours  while 
the  liquiil  cools:  then  it  is  crushed  with  a  p«'Stle  and  filtered  on  the 
jjuiiip  tliroii^'h  a  tiller  that  has  heeii  ii red  against  another  one.  The 
crystals  of  trinitroeresol  are  washed  with  10  c.e.  U/),  dried  at  li.'i  to 
100"  and  weifjhed.  If  these  instructions  r.re  earefiilly  followed.  1.74 
trin.  of  trinitro-/yi-cresiil  are  ohtaiiied  for  eaeli  frraiiime  of  mefacrcsul 
[iresent  in  tlie  mixture  whatever  the  coinposition  of  the  latter.  The 
presence  of  even  10','  plieii(d  does  not  diminish  the  accuracy,  as  the 
picric  ai'id  that  is  formed  remains  in  solution,  liuf  the  iiiefliod  must 
not  lie  applied  to  iiiixtiires  coiitainiiisr  lar^re  aiiiounts  of  ])lieiioI.  This, 
however,  does  not  often  occur  in  practice.  In  such  Siiiiiples  the 
presence  of  plienol  is  detected  by  the  H.!'.  and  also  hy  the  fact  that 
the  nitro  compound  does  not  reininn  solid  in  the  sfeam-oven  at  '.C> 
to  100 '.  hut  melts,  or.  at  aii.v  rate,  forms  a  s:d't  pastt .     Rut  a  cresol 

tl'.--if     .-I'.ufili;     i'c.r    H-.ii    T^'.;-.-l     T-.;:rf     tv^if •.•.•i;;iT-.     VIO    -.;i...-l      '(10.-     n:-..!       i!;,i-.-.   *'..-.-.. 

contains  scarcely  nny  plienol.  always  yields  a  pale  yellow  crystalline 
mass,  the  wcifrlit  of  which  divided  by  1.74  >;ives  the  weight  to  within 


62 


Tin-;    1  i.olATliiN     I'HOCKS-; 


1',  of  tlif  //i-crrsdl  ill  the  iiiixliirc.  It  iii;i\-  lir  well  to  i.'piiil  llwit  not 
less  than  '.tO  v.^'.  of  IIXO,..  is  iisi'il,  niid  pinirod  all  at  oiici'  into  tin- 
rtask  as  (iiiii-kl\-  as  possible,  a  Hask  having  a  very  wide  neck  liein^'  used. 

To  d<'li'niiiiic  all  tlirec  isonieis  liasrjic;:  sejiaratrs  tliu  (/-i-rcsol  coni- 

lilrtcl\-  i>y  n'lxatcd  Iradional  distillation;  the  distillates  lieiiif,'  i- 

posed  i-oUL'lily  of  (in'(  //(■  and  40' ^  /(-eresol  in  wliieli  the  f/i-iresol  is 
di'iei-iiiiiied  as  above.     This  ojxTation.  however,  is  entirely  beyond  the 

skill  and  resource  of  the  avera^'e  ehrmist.     It  is  renilereil  uniK ssai-y 

from  the  fact  that  the  three  ai'ids  iii"ntioned  bear  a  fairly  •  instant 
ratio,  as  before  stated,  in  any  eoimiiei'cial  eresylie  aeid ;  from  tlie 
pei-ccnla^'e  of  lurta-eresylie  aeid  formed,  the  others  may  be  ealeii- 
lated.  These-  three  aeids  ean  be  olitained  in  a  iinre  state,  1  sufj^est  a 
trial  of  them  on  a  small  scale,  and  1  venture  the  ojiiiiion  here  that 
the  ortlio  (-resylic  acid  is  die  one  that  does  the  work. 

Cresylic  acid  should  be  handled  carefully,  as  it  jrives  rise  to  painful 
skin-wounds,  and  may  easily  spla.sh  into  the  operator's  eyes.  It  is 
well  to  keep  a  bottle  of  olive-oil  hands   as  a  r-'iiiedy. 

'v'u.vi.-T.MJ  CuiXj  .s, — Cresylie  acid  is  an  expensive  ri'ajjent,  eost 
at  lea.st  .tl.1'5  i>er  pi'lm  delivered  at  Western  American  mills  in 
j)eace-time.  It  comes  |ii'incipally  from  (iermany  and  En^dand.  A 
search  for  a  cheaper  substitute  has  shown  that  crude  coal-tar  creosote. 
whi(di  is  a  by-jiroduct  of  j?as-work.s.  bla.st-furnaces.  and  s^as-produeers, 
is  |iroiiiisiii^'.  Samples  from  ditl'crent  sources  vai'y  irreatly  in  liipiidity 
and  (diemical  com]iosition  '  nroiiortion  of  jiheiiols  and  cresols  ]M-esent )  ; 
they  well  merit  investisration.  Heing  generally  viseous  they  emulsify 
iiiipert'i'cdy.  especially  in  tiie  cold,  and  while  some  solvent  like  pine- 
oil  oi'  cresylic  acid  can  be  i  iiployed.  such  solvents  are  expensive  and 
tend  to  mask  the  etTect  of  the  original  reagent.  It  is  pn  '  able  tiiat 
the  employment  of  the  moi'e  liiiuid  blast-furnace  creosotes,  with 
]H-eliiiiiiiai'y  heating,  would  be  attended  with  good  results. 

('arbolic  acid  (phcru.l  is  a  homologue  of  eresylie  acid.  It  is 
difticult  to  distinguish  between  them,  the  smell  and  color  being  so 
iinndi  alike.  Ca'-liolic  acid  has  a  soluliility  vai'ying  from  -i.M' ',  at 
ir  to  11. S:!';  at  77'  in  100  parts  of  water.  It  is  easily  broken  down 
by  sulphuric  aeid.  yieldiiitr  oxalic  acid.  It  apjiears  to  be  much  lcs,s 
selective  than  cresylic  acid  in  its  action  on  metallic  su'phiiles.  and  a 
sliirlit  excess  brings  over  a  coneeiilrate  hitth  in  insoluble  matter. 

l''ri,i.-(>ii '^.  My  investigations  eovi'r  Mexican.  Texan,  and  ("aii- 
foi'iiian  crude  oils.  From  .e  known  ditTerence  in  composition,  it  is 
not  suriu-isint'  that  on  any  particular  ore  the  results  ai'e  widely  ditYer- 
ent.     The  metallurgist  should  have  saiiii>les  of  all  three  on  hand  when 


OILS  LSKI)  IN'  THE  FLOTATION  I'KiK  i:ss 


63 


niiiiiiiif;  tests.  Fuel-oils  are  iint  liit;lily  selective  like  ercsylie  aei... 
pine  oils,  etc.,  but  are  strongly  emulsive;  they  secve  the  pui-pnse  dI' 
giving  lioily  and  iiiineral-carryiiig  power  to  the  relatively  weak  l)Ut 
more  st^-leetive  froths;  they  are  ( iieap.  (juiekly  olitainalile,  and.  when 
used  in  moderation.  Iii'iiig  ovei-  little  gangue.  It  is  well  to  inere;ise 
their  tlnidity  hy  stcam-jaekeltiiig  the  eontainer  from  which  they  are 
fed  to  mi.xing-eoinpartnieiit.s. 

(ias  Oil  (stove-oili. — This  is  one  of  tiie  distillati(>n  jn'oduets  of 
erude  oil.  It  is  a  strong  eniulsi''ving  agent,  which  is.  at  times,  most 
useful.  It  is  worth  a  trial  in  running  tests.  It  must  bo  used  in  very 
small  (piantities. 

Crude  Wood  Turi)entine. — This  is  not  tlie  ordinary  spiiils  of  tur- 
pentine. It  is  a  dark  reddish-brown  li(|uid  with  a  pungent  smell. 
Oil  gravit.v-flow  machines  I  have  found  it  of  little  use,  as  its  action 
ill  slight  e.xoess  is  to  bring  over  gangue  freely.  As  an  emulsifier,  I 
niueh  i)ret'er  fuel-oil  or  tar-oil.  On  maeliiiies  through  which  the  tlow 
of  pulp  s  maintaiin  by  meelianieal  means,  it  has  lieen  found  a  valu- 
able reagent  for  the  purpose  of  eontrolling  the  levels  of  pulji,  through 
its  phy.sical  action  on  froths,  hut  this  result  is  achieved  at  t!'e  ex- 
pense of  impure  eonecntrate.  unless  the  agent  is  used  in  the  s*rietest 
moderation. 

I'iNK-OiLs,  Wo()ij-T.\K  Oils,  Fik-Oils,  \Vu.ii)-('Kr.osoTi>,  Etc. — Tiie 
di'struetive  distillation  of  soft  woods  yields  a  large  numi)er  of  pro- 
duets,  and  possible  reagents.  I  have  found  the  oils  derived  from 
pine  and  fir  to  be  more  selective  on  ehaleopyrite  than  on  ehalcoeite 
ores.  Wood-tars  and  tar-oils  are  excellent  emulsifiers.  but  it  appears 
that  the  series  in  general  gives  better  results  on  zinc  and  lead  than 
on  copper  sulphides.  I  have  found  ])ine-oil  useil  in  conjunction  with 
crude  sulphuric  acid  to  give  exeellent  reemeries  on  weathered  ehaleo- 
pyrite ores  where  cresylie  acid  had  been  a  complete  failure.  There 
may  be  some  significance  in  the  fact  that  the  action  of  suli)hurie 
acid  on  teri>eiics  '  •■.;'-oils)  and  phellandrencs  (crude  euealyptus- 
oils)  is  to  give  in  .tli  eases  di|)enteiies  and  terpinenes.-  I  men'ion 
this,  as  euealy]'ti..>-oils,  which  are  prohibitive  in  cost  in  America, 
are.  I  understand,  universally  used  in  eoiijunelion  with  sulphurii'  acid 
on  zinc  and  lead  ores  in  Australia. 

Ai'i'LiCAiULiTV  OF  TIIL  I'uocL.-^s. — T.  ■] .  Hoover  in  the  latest  edition 
of  his  book  on  flotation''  repeats  the  statement  nuide  in  the  iirst 
edition,  that  there  is  a  doubt  if  ehalcoeite  can  be  recovered  succes.s- 


II 


s'Tliorpcs   Dictionary  of  Applied  ('heniistry.'   1913. 
a'Coiicentrating  Ores  by  Flotation,'  1912. 


G4 


TIIK    FLOTATION    PROCESS 


I'ully  liy  tliitiUiiiii.  This  hiii'i'ly  is  ;iii  ovvrsijjrht  :  im  o:if  is  iiiui'c  r.ij.r- 
iii/aiit  than  .Ml-.  Ilnn'.  ,r  ,,f  t|,,.  ircciil  work  iIdir' ill  Hotatimi.  and  I  luivc 
uiily  iiriT  1(1  iciVr  1(1  the  very  iii>rli  recoveries  tiiat  lia\e  heeii  iiuale 
on  a  woikinjr  scale  on  ciialeoeite  ores,  in  Arizona,  at  several  lari,'i' 
mills. 

•  'iilirite  is  considered  a  difticult  mineral  td  reeo\(.r  liy  flotation. 
Ill  tile  case  of  one  ore  that  lias  come  under  my  notice,  in  whicli  the 
ciijinte  occurred  as  a  subsidiary  mineral,  the  savinj^  amoiinied  {,,  a 
small  pereentai:e  only,  cer'aiiily  not  as  miicli  as  an  ctHicieiii  .^iiuie- 
tahle  wiiidd  iiave  recovered.  On  the  silicate  and  earhonate  ores  llieie 
is  |ir(ihal)l\'  no  appreeiahle  recovery. 

.Mi;iii  wicAi.  Sim:  or  tiik  I'laicK.^s.— In  my  opinion,  tiie  devejop- 
iiK  III  of  what  ma,\  he  termed  piieiimat  ic  Holation  processes  \>\  ('iillow. 
Flynn.  'Cowne,  and  others,  constitutes  the  most  distinct  advance  (d' 
recent  years.  'I'liey  consist  of  a  directly  and  clieaidy  ajtidied  supi)l.v 
of  airdiulibles  in  a  liiiely  divided  stati',  to  assist  in  brin<rine;  to  the' 
surface  of  the  pulp  the  already  prepared  sulphides.  The  asiitation 
is  cheaply  and  easily  performed,  and  is  (piite  subsidiary  to  the  acti m 
of  aeration  discussed  above.  1  have  found  a  shallow  troii-rh-aL'iJatoi-. 
with  beaters  only  i)artly  subiiier^'ed.  (piite  suflicieiit.  The  introdoctioii 
of  a  ,jet  of  live  steam  into  the  mi.xinjr  com])artiiient  is  an  adxanlaiie. 
The  pulp  may  flow  throiifrh  tht>  mi.\iii^'  and  a  ration  omjiai'iiiie>:ts 
-  by  gravity  at  the  cxpi'iise  of  a  trifling  loss  of  headroom.  This  less  is 
more  tiian  comiiensated  liy  decreased  power  and  labor  costs,  and 
siiiiplicily  id'  working.  Finely  divided  airdmbbles  can  be  diiveilv 
and  ]ie?-t'eetiy  api)lie(l  tliroiigli  many  forms  of  porous  media  siidi  as 
I'anvas,  eoriinduiii  stones,  silica-tiles,  sandstone  slabs,  etc.  The  mineral 
particles  are  seized  upon  and  at  once  removed  as  concentrate,  witliout 
having  to  be  repeatedly  sub.jeeted  to  a  sort  of  'fractional  distillation' 
as  in  tli"  older  .systems.  It  is.  in  a  way.  the  converse  of  I-;imore's 
vacuum  ]irocess,  and  has  the  merit  of  beintr  jiositive  in  action  and 
under  perfect  control.  Kemarkable  results  have  been  shown  in  the 
economy  of  reagents,  power,  and  labor:  also  in  the  ea.se  with  which 
such  macliines  can  lie  started  after  any  of  these  sudden  stops  in- 
cidental !('  milling  operations. 


rioTM'iiiN    \)V  ((ii'ii;i;   (i|{|; 


65 


FLOTATION   OP   COPPER   ORES 

(From  the  Miiidiij  and  .Srifntiflr  Press  of  May  29,  1910) 


Tlir   Ivliliir: 

Sii- — Tlic  iiiriitioii  lit'  my  iiiiiiit'  in  your  ivceiit  article  on  this  sul)ji'ft 
ti'iiijits  me  t(i  otl'iT  ii  lV\\   remarks  that  may  ho  df  general  interest. 

Pneumatic  flotation  is  already  fully  established  in  a  number  of 
phices  and  the  results  in  comparison  with  the  other  and  older 
schemes  fully  justify  the  opinion  of  your  correspondent  that  it  con- 
stitut(s  tiie  most  distinct  advance  in  flotation  in  recent  years. 

The  tirst  pneumatic-flotation  plant  in  tliis  country  was  erected  by 
iiie  in  February  i:t1-l  for  the  National  v'opi>ei-  Company  at  ^lulhui, 
Malio.  a  description  of  which  lias  already  been  published.  The  re- 
sults were  fuily  up  to  expectations  from  the  very  start.  This  plant 
consists  (tf  S  rougher  aiul  2  (deaner  cells  and  treated  500  tons  per  24 
hours.  A  :iO-hp.  motor  furnished  power  for  all  the  air  necessary  for 
both  ini.xing  and  separating,  and  the  oil  consumption  a\eraged  as  low 
as  0.1  :i  Ih.  of  refined  pine-oil  per  ton  of  ore.  It  wjus  an  ideal  floating 
ore.  Since  then  the  Callow  scheme  has  beeu  adopted  by  nearly  all 
tile  oilier  mills  in  the  Coeur  d'Aleue  for  the  treatment  of  their  Icad- 
ziiic  line  sand  and  slime-feed,  and  has  been  a  means  of  simplifying 
their  plants  antl  adding  greatly  to  tln'ir  recoveries. 

The  other  plants  that  I  have  since  erected  have  followed  the  sjune 
general  lines  as  were  laid  down  at  the  Nat'onal.  namely,  air  or 
tube-mill  mi.xing  and  emulsifying  of  the  feed  followed  by  the 
separatoiy  cells  run  in  parallel.  Kecent  results  at  the  Inspiration 
mine  would  indicate  some  •  Ivantage  (on  that  ore,  at  least)  in  running 
tlie  ceils  ill  series  of  two  instead  of  parallel,  and  without  any  sacrifice 
ill  eapjiriiy  tor  a  certain  set  number  of  cells.  On  an  ore  carrying  a 
large  |)ei-eeiitagc  of  mineral  there  is  not  iiiuch  doubt  that  the  series 
plan  will  give  the  best  results  iiiid  possibly  dispen.se  with  the  necessity 
for  (deaning  the  concentrate. 

The  various  elements  that  com|)ose  the  scheme  in  general  are 
illiistiatnl  ill  tiie  aiccunpanying  diagram.  The  preparation  of  the 
pulp  by  any  form  of  violent  or  propeller  agitation  is  not  neees.sary 
f(M'  good  resul's  with  the  penuniatie  proce.ss.  Where  the  oil  can  be 
introduced   into   the   tube-mill   no    further   refinement  in   mixing   is 

;};■;•;■:;:.;;;;•;.       T;;::;.    :;!'    ;;;;;:■:;;■.    c;;:;:i;;i,    always    be    dr,;vc    •{•.•d     Hi     su."h 

cases  air-mixing  with  the  I'achuca  becomes  necessary. 

A  standard  separalory  cell  has  a  capacity  that   will   varv    froii! 


a 


C6 


Tin:    I-LilTATloN    riidCKss 


li.)  til  I.)  tolls  ipt'  iVcil  [in-  '21  Imurs  wlim  run  in  piirallcl.  (Icix'iidiiig 
of  iMimx'  \i|)i)ii  the  fliiir;ii-trristii-s  nf  the  rvi\.  Two  cells  in  |iiiriil!t'l 
will  li:i\c  aliiiut  the  same  capacity  as  two  c-ills  in  scries.  Init  a  sli;;iitly 
Inuer  tailiiii:  may  lie  exiiecteil  with  the  series  treatment. 

The  idiMius  lueiliiim  in  the  hnttinii  nf  the  cell  is  a  loosely  woven 
panvas-tuill  four  layiTs  thick,  secured  to  the  upper  surface  of  a 
jierforateil  jihite  with  liifurcati'd  rivets  and  washers.  This  is  the 
I)reseiit  staiiiiard  construction  and  has  liceii  ado|)teil  al'tcr  a  ^reat 
many  disa]ii)iiiiitii;^'  experiiiients  with  other  materials.  It  is  irood 
lor  .1  three  or  four  months"  continuous  caiiipaiirn.  and  hecomes 
inopcra.tiv;'  only  thi-ouL'h  the  iilliiii.'  ii])  ot'  the  pores  li.\-  dust  that  has 
lieen  intriidiiced  hy  wa.\-  of  the  Idower.  Four  or  live  pounds  of 
air  I'l-essure  is  am|)le  in  all  cases  to  ^'ive  the  ])roper  aeration,  the 
(pianiily  of  air  varyini:  from  (i  to  M  en.  I't.  per  sijuare  foot  of  lilaiiket- 
surl'ace.  When  the  cell  is  iiroi)crly  ad.justcd  and  doini;  its  hest  work 
there  should  i)o  no  violent  a^'itatioii  with  the  c  11.  hut,  only  such 
agitation  as  is  incident  to  i)riiper  aeration.  Any  violent  airitation 
jiroducintr  a  sui'i;inir  of  the  liquid  contenls  has  pi-oved  detriiiieiital 
to  irood  results. 

A  slope  of  :!  in,  per  foot  on  the  liottom  has  liecn  I'oiind  sutlicieiit 
to  treat  all  oniini'ry  ores  after  crushing;  throiiirh  :iii  or  4<'-iiiesh. 
Treatinjr  coarser  inatei-ial  or  ores  that  contain  a  larfre  ])ei'ceiitaire  of 
iieavy  i;an<riic  (such  as  in  tlu'  CiiMir  d'Aleiiei.  it  has  heeii  I'ound 
advaiitaiieous  to  increase  this  to  as  much  as  4.1  in.  per  foot  to  jirevcnt 
the  hlanketin^'  of  the  ])orous  medium  hy  coarse  sand  eolleclinir  on 
the   l.ottom. 

The  air  from  the  sei)aratory  cells  has  so  far  lieeii  furnished  frmii 
I)ositive  hlowers.  tiut  tiirbine-lilowers  would  he  preferahle  where 
the  si/i'  of  the  installation  .just'lies  their  adoption.  -\n  air-pressvire 
of  l.">  111,  is  ami)le  for  the  Pachuca  ini.ver  and  2.')  cii,  *'t.  of  free 
a  •  per  minute  is  sui'ticient  volume  for  mi.\in<i  'I'tO  tons  of  iiiiinis 
4S-mcsh  I'lilp.  and  of  course  slmuld  he  furnished  I'rom  a  low  pi-cssure 
compressor. 

The  di  nsity  of  the  pldj)  may  var.v  from  '2\  :1  on  ,  sanily  feed 
up  to  7  :  1  on  a  strictly  slime  I'eed.  The  particular  d.  ii--ity  is  not 
a  m.'itler  of  so  much  impoi'tance  as  tliat  t!u'  supply  of  pulp  shall 
lie  unifoim  as  to  its  deiisit.v.  since  each  variation  in  the  density 
re(plires  a  rcad.just lie  nt  of  the  oil-sujjply.  the  ipiantity  of  oil  rcipiired 
incrcasiiiir  in  proportion  to  the  inci-ea.sed  volume  of  the  pulp 
independent  ol'  its  solid  content. 

The  advantai;.'s  ol'  the  iineumatic  scheme  are  frreater  recoveries. 


ri.dTATlMN   OF   Cnl'I'KR  ORES 


67 


JojDjiSy    v}nif3iy  ,g/.,.St- 


■it 


fi.S  THE    ri.nTATION    l'U()CK>S 

I'^s  ml.   !_'ii'iitri-  -,iiii|)lirii y.   ainl    lc>.s  skill    ri-ijuwril   tn   npiTiiti'.      The 
ilitVriciirr  in   wrar  ,'iimI  Iiai-  is  iilivioiis. 

I'l-ddf  111'  till'  iijiiiasiil  ri'i-Dvci'ii'S  is  shown  in  Talilf  I.  wliii'li 
ir|irrsriils  u  :!()-iia.\'  I'Dinprtitinii.  Ft  is  iiDticfiihlo  that  this  im-rcase 
ill    I \ri'y    lii's   iirinripally   in   tlir   liinT  and   sliiiii'   pnrtiniis  of  tln' 

T\nrK  I 

^^^l^-l-.  ok   i.miinc  —  riinuvinv   I'Kkiod 

Total  copper  Copper  oxidi' 

Flotation  tailiim.  Table  tailiiit;.     inroniblneii 

Mesh,  Wei-ht.        A. P.  P.P.  A. P.  P.P.         tailin:,s. 

'.'<  ■■  ''c  '',  <7o 

—  •;:.    7.0  n.3.s  o..";;  0.30  1x29  0.1 ;; 

—  100  15.0  0.43  0.44  0.29  0.24  o.i:i 

—  150  12.0  0.44  0.3O  0.30  o.2.'i  o.u; 

-r   200  !i.s  0.54  0.44  0.34  o  -w.  0.22 

—  200  5i;.2  0.5.S  0.42  0.56  0,4;;  "      0.33 

A  ,era^e,  all  sizes.  lO'i.o  ...  .,  0.44  0.35 

T  villi;   11 

A\M.V-.I^    (IK    COM  F.MRVIKn 

l-"or  tile  saioe  period 

C'li,  Insol  .  FV.  S, 

.V^'itatini;  iiroopss   ;;2.34  21!. 50  15.01  22.79 

Pneuni.-itir   i.iocess    31.24  2:!. 70  Hi. 79  23. S4 

The  festiltiii^'  coiicontrates  I'niiii  the  same  eoinpctitioii  are  shown 
in  Tahle  II.  wliieji  inilieates  that  tho  slightly  h>\ver  firade  of  coppei' 
is  more  than  otVset  hy  tlio  lower  insohihle  and  higher  iron  contents. 

'I'lie  ])i-()(if  of  lower  ])ower-ronsMni])tion  is  that  the  10  cells  of  the 
Xatiiinal  ('(ii)per  (  o.  witc  run  with  a  iiO-l  ,•.  motor  and  treated  .lOO 
tons  |ier  d,i\' :  the  -.niie  tonnaire  Itcated  hy  a  pi'o|)eller  inaehine 
would  ha\"  taken  close  on  to  KIO  hp.  This  figure  has  also  lieen 
eontirmed  at  other  plaees.  The  pow.'r  nHjuired  will  vary  from 
2  to  :j  kw. -hours  per  ton. 

The  froth  produced  from  llie  ])eiiuniatic  j)rocess  is  much  more 
ejiheiiiiral  than  that  iirodiiceil  hy  iH-opeller-agitation  nuiehiin's.  a 
self-evident  advantage  when  it  eniues  to  collecting  and  handling  the 
restdtiiig   eoiieent rates. 

Regarding  oils  the  remarks  of  your  eoi'trihutor  witli  regard 
to  eresylie  m-'ul  and  the  methods  of  analysis  given  are  e.\treniely 
interesting  ami  v.iln.ilile.     So  far  as  my  own  expei-ience  goes.  I  have 


Fl.iiT  \TI(iN    ny   ciin'KK  (ilil  ~ 


6» 


li 


not  found  crtM  lie  acid  indispensable;  at  the  present  time  and  priee 
it  is  out  of  the  question  as  a  flotation  apciit ;  it  Wduid  s«-eni.  moreover, 
that  the  same  results  can  he  obtained  by  the  use  of  less  retined  and 
expeiisive  reagents.  In  the  Coeur  d'Alenc  on  the  zinc  lead  ores, 
wood  creosote  seems  to  jrivc  tlic  best  results.  Tlic  Inspiration  us«'s  a 
mi.vture  of  HO';  Kl  Paso  coal-tar  and  20',  cieosotf.  At  one  time 
we  used  a  2i  to  5',  addition  of  pine-oil,  but  this  has  since  been 
found  unneccs.sary.  A  mixture  of  20^t'  pine  oil,  20^;  cresol.  and 
(iO';  carl)olii'  was  trictl  exi>erimentally  at  the  Miami  mine.  l)Ut  just 
as  good  results  were  obtaiui'd  by  substituting  Salt  Lake  creosote 
for  the  cresol  and  carbolic.  These  are  both  ehalcocite  ores  with 
some  pyrite  :  the  ehalcocite  is  easier  to  float  than  the  pyrite.  The 
pulp  is  neutral.  The  recoveries  will  approximate  Mo'V  of  the 
sulphide-copper  contents. 

I  have  tried  a  great  many  of  the  wood-oils,  both  the  steam-distilled 
retined  products  and  also  the  destructively  distilled  cnidc  tars  and 
creosotes,  \m\  have  generally  come  back  to  the  coal-tar  mixtures. 
The  pine-tar  ]ii-oducts  are  excellent  frothers  but  the  coal-tar  products 
seem  to  act  as  collectors,  and  a  combination  of  the  two  is  often  neces- 
sary. Acid  sludge  has  been  u.s<'d  with  good  success  on  Butte  copper 
ores,  but  the  disadvantages  of  this  are  that  it  recpiires  heat  and  also 
additional  (pmntities  of  acid  to  get  the  best  results.  This  means 
working  with  an  acid  pulp  and  prevents  the  introduction  of  the 
oil  into  the  crushing  plant  because  of  the  destnietive  effect  of  the 
acid  on  anything  but  a  .silex-lined  mill.  Some  ores  work  best  in  an 
alkaline  pulp  and  others  in  a  neutral  one.  My  own  opinion  is  that 
in  most  cases  the  same  results  can  be  obtained  in  alkaline  or  neutral 
pulp  as  can  be  obtained  in  an  acid  one  and  the  advantage  of  an 
alkaline  or  neutral  pulp  is  self-evident. 

In  one  plant  we  had  an  interesting  experience  of  this  kind.  The 
\\afer-su])ply  was  limited  and  all  the  milling-water  was  returned 
back  to  the  mill.  The  flotation  results  gradually  deteriorated  as 
the  mill-water  accumulated  acid;  ihe  more  acid  it  got,  the  poorer 
the  results.  Lime  was  then  added  in  the  tube-mill  and  the  pulp 
ma<le  alkaline;  this  produced  a  tremendous  increase  in  the  volume 
of  froth  made,  but  without  any  definite  improvement  in  the  tailing. 
By  redticing  the  lime  and  allowing  the  pulp  to  work  back  to  the 
neutral  point  the  results  again  became  normal;  and  it  is  at  the 
nciiirni  poini    Uial  we  now    do  our  iiesl  work. 

Tlicre  is  a  great  deal  of  work  yet  to  l)e  done  with  oils,  especially 
in   comixMinding.   modifying,  and   in   making  tlieni  miscilile  without 


70  THE    FLOTATION    I'KOCKSS 

lii'iil.  'I'lic  li^rht  ('(iiiihiiiatioM  ot'  oil  is  cvcrylhiiij; :  tln'  (|uaiitity  per 
foil  lias  ii'ss  iiiHiU'iirc  oil  the  results  than  the  rifrht  mixture.  The 
etVeet  with  loo  iiiueh  oil  is  iiei'lianical  i-allier  than  iiietallur^'ieal ; 
too  iiiiieh  oil  produces  so  uuhh  froth  that  it  overHows  everything; 
anil  eaniiot  be  handled  in  the  plant.  Smnr  experiments  made  in  this 
(lireelion  <;ave  the  followinfr  results: 

Grade  of  Extrac- 

Oil  \H'V  ton,  foiurnlrate.  tion. 

II).  '/r  ': 

2    io.or,  ito.ii\ 

30     9.S2  !tr,.!)l 

Km    7.95  n:!.4t; 

Hut  this  is  a   lar^'e  suliji'et   and  altotretlier  lieyond   the  seo|)e  of 
these  random  remarks. 

J.  M.  C.viJ.ow. 
Salt   Lake  City.  A|>ril  2:?. 


I'HKKl.KKNTIM.    KF.oT  VIIiiN 


71 


PREFERENTIAL   FLOTATION 

By  0.  ('.  H ALSTON 
(Kioni  the  MtiniKj  tiiul  Snriittic  I'l'ss  of  .liiiie  -'i,  I'Jl.")) 

•I.NTKoDrcTioN.  ' I'ri'tVrciitial '  Hotatioii  is  a  specialized  applica- 
tion of  the  flofative  i)rincip]e  in  the  .se])aratiori  of  minerals  from  their 
ores.  It  fjaint-d  its  lirst  wide  use  as  a  name  fur  certain  methods  of  float- 
ing nunerals  in  ctmiicitioii  witii  tiie  Ilorwood  j)roces.s  mentioned  below. 
'Selective'  flotation  has  come  to  mean  (Ity  common  consent)  the 
flotation  of  valiialile  nnnerals  (generally  the  metal  sidphides  i  in 
the  presence  of  undesirahle  fran^ue-minerals.  '  IVefercntial'  flotation 
is  the  flotation  of  one  of  the  ordinary  Sfdectivel.v  flotative  minerals 
in  the  presence  of  another  similar  mineral.  Thus,  a  iiii.xture  of 
palena  and  sphalerite  can  he  floated  'selectively'  from  a  gangue  of 
granite,  limestone,  or  otiier  eomnion  ganpne-matcrial,  while  galena 
may  he  floated  'preferentially'  from  a  ini.xtnre  of  galena  and 
sphalerite. 

On  account  of  the  great  interest  manifested  in  this  subject  of 
late,  I  have  thought  that  the  following  review  of  proposed  or 
operating  processes  might  be  of  interest.  This  review  is  largely 
a  compilation  of  ])atent  literature,  but  it  might  he  well  to  call 
attention  to  the  fact  that,  at  present,  patent  literature  is  one  of 
the  best  sources  of  information  on  the  subject  of  flotation  for  one  who 
does  not  have  the  opportunity  to  visit  at  flrst-hand  the  localities  where 
the  practice  c.f  flotation  is  l)eing  used  or  tested. 

C.vTTEUMor.K.  In  IftO-i  Cattennole  (U.  S.  Patent  70^,250)  made 
one  of  the  earliest  proposals  for  the  preferential  flotation  of  minerals. 
The  method,  as  he  (U^scribed  it,  was  not  exactly  a  flotation  method, 
but  it  involved  most  of  the  underlying  principles  of  flotation,  and 
lience  is  of  interest  in  this  connection.  As  stated  by  Cattcrmole: 
'"The  invention  relates  to  the  classification  of  the  nu'talliferous  con- 
stituents of  ores  which  have  been  separated  from  gangue  by  oil  or 
similar  matter,"  and  "consists  in  fractionally  removing  the  difTerent 
constituents  from  th(>  agglomerated  ma.s.s*'s  liy  freeing  the  constituents 
in  turn  from  oil,  and  thus  obtaining  them  in  a  separalile  condition 
by  the  use  of  emulsifying  agents  of  varying  strengtli  and  activity, 
preferalily   in    conjunction    with    an    alkali."      ''In    carryinsr   out    fhp 


•Contributed  l)y  the  Dpiiartnient  of  MetaMiirgioal  Rese.Trch,  fniversity 
of  rtah.  I).  A.  l.yon,  im'lalliir«iat  in  cliarse:  O.  V.  RalKton,  assistant  metal- 
lurgist.    I'ublished  by  permission  of  the  Director  of  the  V.  S.  Bureau  of  Mines. 


72 


rilK    Kl.dTATluN    I'HIK  !■>> 


|iiiiccss.  Ilir  iiiilallil'nnus  liijillir  Mtrtrloiiicriili-il  Ky  nil  is  nii\i'il  mikI 
af;itiili'(l  Willi  ;i  siiiuiioii  of  an  t'liiuisifviti^  ii^'riit.  siirli  as  a  suliilili' 
siM|i  alkaliin'  nliali'.  I'nr  txaiii|ilr.  In  wliidi  a  !•■  itaiii  proixntioii  nf 
soliililf  alkali.  pretVraMy  caustic  pntasli  or  Mxia.  lias  been  acMivl." 
■'It  is  I'diiiiil  tlial  llif  iMiiii'i'als  vary  in  liirir  atliiiily  for  nil  i'iiipinyi>il 
in  the  altnvc  inanncr.  and  thus  tiy  Ircatinn  the  oily  niassis  nr 
(;raiiul<'s  in  tli<  liist  |ila<i'  \«itli  an  alkaliin  iiiiiilsilyiiit;  snlutinn  nl' 
a  certain  striiit-'th,  the  mineral  nl'  least  atlinily  can  he  se|iarale(l 
theretroiu.  and  by  increasi:.^'  <he  strength  or  inodil'yitif;  the  itrnpnr- 
tinns  nt"  the  bi-eakinjr  dnwn  solution  ste|)  liy  ste|).  the  various  iiin- 
stituiiits  can  tic  thrown  out  in  the  oi-der  nl'  tiieir  inrreasiiiir  alliiiily." 

('aiteriiiole's  jiatent  came  at  a  time  when  the  proeess  was  truly 
'nil  tlolation.'  as  the  use  of  small  amounts  of  oil  bad  not  beiii  made 
Micc'essfiil,  and  the  partieular  mi'thod  of  tlotatinn  which  he  had  in 
mind  in  this  patent  was  ])robably  that  described  in  one  of  his  other 
paleiits.  in  which  the  minerals  desired  were  flocculated  or  irraiiulaleil 
iiy  the  Use  of  oil  in  lar^'er  amounts  than  tln'  ])resent  methods  of 
flotation,  that  is,  in  amounts  up  to  o',  by  wei>rlit  of  the  re.  and 
these  granules  woubi  sink  of  their  own  ueij.'ht  in  an  upward 
moving'  current  of  water,  such  as  that  of  a  classifier,  while  the 
untloceulatcd  tranj;ue  woidd  rise.  He  made  the  wording  of  bis  patent, 
however,  luoail  ennuirh  to  cover  the  treatment  nf  i)rodiicts  as  obtained 
by  true  flotation. 

As  an  example  of  the  workinjr  of  his  jiroeess  he  uses  an  ore 
(•onsisting  nf  a  silic-ioiis  fxanu'ue.  zinc-blende.  co|)|ier  pyrite.  and  u'aleini. 
which  has  been  treated  with  an  oil  for  the  granulation  of  the  mineial 
stdphide  particles,  and  tlie  latter  separated.  The  oil  i.s  pret'erably 
one  that  is  not  readily  eiiiulsilied.  such  as  a  liydro-earlmii  nil,  which 
will  jiivc  a  wide  raiifTe  of  stren<;tli  in  the  solutions  used  later-  in  the 
breakinsr  down  of  the  ^rranules.  The  compntmd  graiiuli-s  .ire  run 
into  the  tii-st  ajritation  a!)|)aratus  where  they  are  aj;it,ited  with  a 
sohition  containii'-sr,  say.  CTo';,'  alkali,  by  which  the  zinc-blende  is 
"dropped  nut,"  '\'\\f  lemaiiiiufr  trranules  ai'i'  jiassed  into  the  uext 
similar  ajjpai'atus,  in  which  a  solution  eoiitainin<;  l.'J'^,'  soaji  and 
I..""';  alkali  is  used.  Here  the  eop])er  pyrite  is  freed  and  ■inl.\'  the 
pramdes  of  paleiia  remain.  As  Cattcrmole  proposed  the  use  of  so 
much  oil.  it  had  to  ]i(>  recovered  b.v  the  use  of  stronfi  alkali  solutions. 

The  rules  foi'  ])roportioiiiiifr  the  solutions  took  into  aeenunt  the 
iiiieness  nf  tiie  nrc,  ilie  reiainc  ]iroi>ori  ions  of  iiic  minerals,  liieir 
jtliysical  condition  and  chemical  composition,  also  the  kind  of  oil 
and  I'liiulsifvinir  at'eiits  used,  and  the  alkali  selected.     The  liiicr  the 


1 


riiLKKKKN  n  \i.  I'f.iirv  rroN 


73 


(III'  thr  limn'  ciiiupact  and  colicsivo  the  iframili's  fniiin'ii,  ami  lifin'c 
till'  si  milliner  the  wdutioii  reciuiri'd  to  Ijreak  tlu'iii  down.  With  t^raiiuli's 
liiitri  !>•  of  fralena.  which  breaks  down  with  difltit'iilty,  stronger  solutions 
arc  ncct'ssary  than  I'or  those  luMsistinir  iiiaiidy  nl"  .sphalerite.  With 
aniiiiiil  111'  veffi'ti.l  oils  that  emulsify  easily  the  hri'aking  down  of  the 
jTraiiuies  will  he  too  rapid  for  coiivenienrc.  Tjie  iieavy  ri'sidiiuni 
nils  and  the  heavy  hydro  earlion  oils  are  the  best.  Oils  may  Ic 
lili-ndcd  advanta^feously  for  this  purpose.  An  alkaliin'  solution  of 
till'  oil  used  in  granulating  is  hest  for  emulsifying. 

Wiii'tlier  or  not  Cattermole's  proeess  was  ever  applird  is  not 
kniiwn  \i\  nil',  luit  it  is  not  impossilile  that  its  i)rini'ii)li's  may  he 
applied  to  modern  tiotation  froths. 

Wi  .\  iwuurii.  Following  the  l'.  S.  patents  in  their  ehronological 
(inler.  the  next  is  .No.  ICiS.Tiri.  of  VM'J.  taken  out  l)y  II.  A.  Wentwortii 
and  assigned  to  the  IIuflF  KleetroKtatie  Separator  Co.  It  "relates 
to  the  separation  of  the  ingredients  which  constitute  ore  nii.xtures, 
and  partiiularly  to  the  separation  of  sulphide  ores  from  each  other." 
'■'I'lie  process  consists  in  the  preliminary  treatment  of  ore  mixtures 
eoiiiaining  .several  sulpiiides,  which  converts  some  of  the  sul{)hides, 
siiperliiially  at  least,  into  metallic  compounds  which  are  ditrerentiated 
in  their  behavior "  with  respect  to  flotation  processes  as  commonly 
practised.  To  use  the  words  of  a  later  patentee,  Mie  surfaces  of 
such  minerals  as  galena,  pyrite,  and  chalcopyrite  are  "deadened'  by 
a  Very  short  and  slight  roast  in  a  roasting-furnace,  while  the  sphalerite 
is  unat^'ected.  Thus  the  sphalerite  can  be  removed  by  flotation  from 
such  an  me.  leaving  the  other  suli)hide  minerals  to  be  removed  by 
other  meaiis.  A  few  minutes  heating  at  a  dull-red  heat  has  been 
loiiiid  to  lie  sutlicient. 

This  is  a  tyjie  of  proeess  that  has  been  tried  in  Australia  under 
tile  name  of  the  Ilorwood.  It  is  further  described  under  that  heading 
in  this  paper. 

li  v.\i  U.K.  The  same  idea  underlies  the  next  patent,  which  is 
No.  Ii4!l.(>(l2.  of  litlO.  taken  out  by  A.  S.  Ramage  and  asvsigned  ti)  the 
Chemical  Development  Co.,  a  Colorado  corporation.  "This  proeess 
has  for  its  ob,ject  the  separation  of  the  valuable  minerals  from  such 
ores  as  chalcopyrite,  bornite,  or  crul)escitc,  and  mixtures  of  the  same 
with  pyrite,  in  which  ores  the  copper  is  in  chemical  combination 
with  the  iron;  and  also  from  such  ores  containing  zinc-blende.     The 

lueliiml    iS    riiSO    appiiertiiie    to    OOUlpOUiUi    ores,    SUeil     nS    tiiOst;    <ii     ihe 

Cobalt  district  and  other  sulph-arsenides. "  "The  principle  of  the 
process  is  founded  on  the  combination  of   fractional  roasting  with 


t 


4 


74 


TIIK    KUlTATKIN     ritOChSS 


cliciiiii'iil  HiialiiiK"'  liiiiiiaf.'i-'s  iiit  iii(liicliiiti  of  tlic  liriii  ' '  tiiU'liiiriiil 
rnastiiis;"  is  particularly  I'cliiituiis,  as  it  iiKin-  aci'iiraldy  tlcNcrilics 
tlif  iiirtlKiil  than  (liMN  tlir  hrm  ' '  prrfin'ritial  tliitalinn,"  usf.l  by 
ll(ir\V()i)(l. 

HaiiuifTi'  tli'scrilicil  lln'  proitss  \t\  tin'  use  of  tliri'c  cvaiiiplcs.  wliidi 

iiri'  (Iccidfdiy  iiitcnsliiis;.     The  lirsl  cxaiiiplc  is  nl'  an  on itairiiiik,' 

ii-dii  pyritf  ami  (•lialii>pyrili'.  '.villi  a  nuitriit  uf  aliout  •'*',  inpix'- 
and  .in  to  4(1';  snliiluir,  Tlu'  ore  is  roast. d  at  alxtiit  a  nil  liiat  lont; 
fnoiidh  to  dccoiiiposc  tiif  pyritc  siitrlitly  and  not  alff't  the  rlialcopyritf. 
•■The  liiiriit  ore  is  then  eruslied  to  at  least  I.')  mesh  and  |)asseil  tliroiijrli 
II  solution  of  aeid  snli>liate  of  soda  and  nitrie  arid  (the  solution  lieins; 
formed  by  addin>r  nitrie  aeid  to  sidphate  of  soda),  whieli  solution 
is  kept  near  the  lioilin^'  jxiiiit.  The  eopi)er  suljiliiile  iiiiiiiediately 
rises  to  the  loi>  of  the  hath  and  eaii  he  skimmed  otT."  The  eojjpiT 
dissolved  in  the  hath  can  lie  reeovere.i  in  known  ways.  This  im-thod 
of  notation  I  hot  aeid  hath-  is  not  new.  Iiavin<;  been  patented  by 
I)e  Itavay.  I'otter.  I)idi)rat,  and  others  The  fraetional  roastinfr  had 
been  previously  patented  by  Wentworth.  and  so  the  only  thing 
that  seems  new  is  the  eoiiibinatioii  of  methods. 

A  seeond  example  is  that  of  an  o.-e  eoiitainin<,'  i)yrite.  ehaleoj.yrite, 
and  /ine-lilende  in  (piaiitity.  The  (U-e  is  roasted  at  a  temjieratiire  of 
not  over  60()°('..  so  that  otdy  the  iron  pyrito  is  deadened.  The 
roiisted  ore  is  then  subjected  to  the  acid  su!i)lii<te  of  soda  solution 
for  flotation  of  the  unchan^'ed  sulphides  of  zinc  and  o(  copper.  This 
product  is  then  roasted  at  about  7t»0'  ('.  \intil  ail  of  the  zinc  suljihide 
is  (leeomposi'd  and  the  copper  siditliide  uueliauflfil-  This  mixture 
is  treated  with  a  solution  of  dilute  sidi>hurie  acid  for  the  dissolution 
of  the  zinc,  to  bo  recovered  from  solution  by  any  familiar  process, 
such  as  .■lectrolysis,  the  copper  sulphides  being  sent  to  the  copper 
smelter.  There  are  certainly  most  interesting  facts  disclosed  in  this 
()atent.  The  great  resistance  of  copper  i-:ulphides  to  the  roasting 
process,  as  eompared  with  the  suli>hides  of  zinc,  is  something  new 
and  will  be  a  most  valuable  characteristic,  if  true. 

The  third  example  is  that  of  the  ores  of  the  Cobalt  district, 
Canada,  where  eobaltite.  niccolite.  ehalenpyrite.  pyrite,  and  native 
silver  occur.  All  the  sidphide  and  sulph-.-.rsenide  minerals  are  floated, 
leaving  the  silver  in  the  gangue.  The  sulphides  are  roiusted  at  about 
800°  C.  and  everything  is  decomposed  except  the  copper  sulphide, 
which  <'an  be  tloated  trom  the  calcine.  Again  «e  imve  meniiou 
of  the  almost  incredible  property  of  copper  sulphides  to  resist  roasting. 

The  next  patent  was  that  of  II.   A.  Wentworth.  amplifying  on 


I'KKFKKKNTIAI.    KI.<iTATl,,N 


75 


liis  loriiKT  patent  in  cliiiniirii;  tin-  siipcrlicial  I'liciriicjil  cliiiiinc  of 
minerals  a.s  n  ini'tiiod  nf  separatinff  tliein  preferentially  l)y  Hotation. 
He  liad  in  mind  partieu'  ly  the  treatmciit  of  the  ore  with  chlorine, 
whiell  Udlild  sink  when  ilijeeted  to  a  Idm-rtotatlon  proee!i,s,  while 
oilers  would  have  th'Mr  flotntive  |>ropertie.s  enhanced.  As  an  example, 
a  mixture  of  zinc  and  iron  .sulphides,  when  treated  with  chlorine  ^'as 
in  a  .slit;htly  damp  slate,  is  so  altered  that  the  hlende  will  Hoat  on  a 
lilmflotation  machine  much  helter  ♦'  ii  before  treatment,  while 
the  pyrite  has  a  coating  formed  over  its  surface,  whii'ii  is  much 
more  easily  wetted,  so  that  if  will  sink.  Still  a  further  example  is 
the  a[>plieation  to  tlic  s<'paration  of  pyrite  and  ehalcopyrite.  The  latter 
is  attai'ked  nuich  .slower  than  pyrite;  hence  it  can  he  floated  when 
lioth  are  present.  A  similar  behavior  of  the  minerals  is  ob.served  when 
lliev  are  su.spended  in  wafer  eontainin>r  di.s.solved  chlorine  in  the 
proper  concentration,  but  the  best  work  seems  to  be  done  with 
minerals  fed  onto  one  of  the  film -flotation  machines,  such  as  that  of 
n.  Iv  Wood  (d'  Denver,  althouKh  Weiitworth  pives  the  (lesii;n  id'  one 
of  his  own  in  the  specification.  It  is  easy  fo  .see  that  with  chlorine- 
water  and  one  of  the  mechanical  frofhintf  methods  (d"  Hotation  the 
soluble  coatiiifp.  that  are  formed  on  the  surfaces  of  the  iiunerals 
would  be  simply  washed  off  and  the  preferential  part  of  the  flotation 
lost.  Tests  in  our  laboratory  seem  to  show  this.  So  far  as  is  known 
to  me.  this  process  is  not  beinjf  useil. 

HoRwooD.  This  process  of  preferential  flotation  is  practically  the 
same  as  that  described  under  Wentworth  and  RamaKo.  It  has  been 
worked  for  some  years  in  Au.stralia  and  received  careful  tistiiiK 
by  the  Zinc  Corporation.  It  depends  upon  the  'deadenins;'  o{  palena 
ami  j)yrite  in  a  slioit  roa.sting  at  .'!()()  to  .')00"  ('..  whereby  the  fralena 
is  coated  with  lead  sulphate  and  the  pyrite  with  iron  oxide,  while 
the  sphalerite  is  unaltered.  This  allows  a  sepaiation  of  the  undesirable 
zinc  fnmi  the  lead-iron-silver  jiroduct  and  allows  their  s«>parate 
marketing.  This  process  has  received  more  cai-eful  attention  than 
any  other  process,  and  reference  to  original  articles  is  best.f  Accord- 
ing to  the  data  given  in  some  of  this  literature,  it  appears  that 
it  is  pos.sil)le  to  take  a  flotation  concentrate  containing  36%  Zn,  15% 
Pb.  and  22  oz.  Ag  per  ton,  and  divide  it  into  a  zinc  product 
running  as  high   as  50%   Zn,  7%   Ph,  and   1.5  oz.   Ag,   and   a   lead 


I 


tT.  .1.  Hoover,  Concentratine  Ores  by  Flotation";  ^fi>l.  ,1  Fiin  Wnrhl,  jnK- 
IS.  1914,  p.  96;  Enfj.  ,(  Min.  Jour.  (1914),  97.  p.  120S;  Minitifj  and  Scientific 
Press.  April  18,  1914.  p.  657;  Metal,  d  Chem.  Eng.  (1914),  No.  12.  p.  350 
and  592. 


THE    FLOTATION    I'ROCESS 


l.nMu.l  .ontiium.-  :i>'  IM..  >',  Zii.  au.l  42  o/..  Ag  per  ton.  Tins 
is  of  K'lvi.t  iiitrnst  In  all  pro.lucers  of  -wiuplex  sulphiJo'  oivs.  as 
the  miUiiijr  <'f  coarsely  crystalliiu-  material  has  presented  iiiueli 
dirtieiiltv  in  the  past  lor  the  reason  tliat  some  linely  divided  material 
1  slime  is  hound  to  form  in  crnshmg.  and  while  the  eomliiued  lead 
and  /in.-  sidi)iiides  ean  he  Hoated  nowadays  without  much  ditlieiilty, 
Ihr  nnxture  is  of  far  less  valne  than  the  '.v.o  minerals  separated. 
'I'liis  -s  important  enough,  not  to  speak  of  the  possibility  of  treating 
III.-  naeroerystalline  sulphide  ores  and  those  containing  gangiie  of 
high  si.eeilie  gravity,  sueh  as  harite.  While  dotation  lias  been  a 
boon  to  the  eoneentration  of  all  sulphide  slimes,  preferential  tiotation 
is  nm.h  more  imp.vrtant  for  the  ores  eontaining  undesirahle  coni- 
hinations  of  suli)hid.'S.  Hen.'.'  Horwo.id's  work  should  receive  th.' 
hiirhfsl   praise. 

Another  detail,  as  regards  this  pro.'ess,  is  that  ',):>  lb.  of  sulphuric 
a.i.l  i>.i  1..1;  of  .-ri'  is  neces.sary  an. I  2  t.)  .i  lb.  of  oleic  acid  for  the 
ri..t:iii.m  «\-  th.'  unalteiv.l  /.in.'.  All  of  this  appeared  in  Horwood's 
rirst  patent.  No.  1  .l)20,;{.');{.  of  V.)V2.  and  he  later  .ame  mit  with 
iMipi-..'v.-m.mts  on  the  process  in  patent  No.  1.108.440,  of  1914.  In 
this  l.il.r  patent  ii"  state.l  that  he  had  found  there  was  a  tendency 
r,,i-  th.'  silver  to  f.illow  the  /..ne.  which  is  undesirable.  Imt  that  this 
,,,ul.l  li.'  prevented  by  simply  wa.shing  away  all  soluble  salts  on 
il,..  roiu'cnliate  bef.ire  il  was  subjeete.l  to  the  deadening  roast.  This 
reduces  the  amount  of  oxi.li/ed  zinc  formed,  and  lo.st  by  so!-.<tion  in 
the  dilut.-  a.'i.l  in  the  mill-wat.T.  as  w,"ll  as  allowing  tli."  silver  t.) 
become  deadene.l  t..  a  greater  extent.  He  also  found  that  the  most 
sn.-<-.'Sslul  flotation  t..ok  ]da.-.>  with  tli.'  ])ulp  at  a  temp.Tature  of 
about    120    F. 

It  will  be  seen  that  th.-  Horwood  process  has  been  applied  only 
1.1  .-.Micentrat.'s  from  previous  tiotation  or  from  otlier  concentration 
pro.-esses.  This  is  the  logical  i)la.'.'  t.)  aj.ply  it,  as  there  is  no  ol)ject 
in  h'aving  a  n.m-H.itativ.-  galena  .ir  other  suli)hide  mixed  with 
gaiigue.  by  using  I  he  pn>.'ess  ..n  crude  mv  ',  ■  ■•  same  remark  applies 
to  m:iny  of  th.'  .>tlier  pr.i.-esses.  To  be  sure,  there  has  l)een  some 
suec.-ss  in  ih.'  Australian  mills  as  well  as  in  the  United  States  in 
the  treatment  of  mixed  galena-sphalerite  oncentrates  from  flotation 
maehin.'s  ..n  .■.in.'..iil rating  tabl.-s.  As  an  .'xamjile.  the  Tiii.her  Uutte 
mill  is  milling  Ih.'  tlotati.m  .■.Mic.'iitrat.'  .)f  a  /ine  ore  ontaining 
some  /.ill.'  coii.'entrale  .-arrying  ^V ;  Zn.  l.o^;  Vh.  and  ^'"<  insoluble, 
llow.'ver.  this  method  has  not  always  ni.^t  with  th.'  best  r.'sults. 
aii.l    wh.'i-e   the   proportiiuis  .if   l.ti.l    ao.l    /in."    in   or.liiiary   .■.imi)lex 


M^ 7' 


I'REFERK.VTIAI,    FLOTATION' 


siilpliidu  (•oiiceiitrati'S  are  al>i)ut  ciiiial  it  is  (iiiito  lianl  to  gvi  two 
products  that  are  sutlieieiiliy  pun'.  VVIiere  it  can  lie  done,  it  is 
certaiiily  more  desiraliie  tiiaii  the  more  complex  traetioiial  roasting 
and  preferential  Hotation  i)roees8e8  of  llorwood.  Wentwortli,  and 
Kainaj^e. 

Lystkk.  Tills  is  another  process  that  lias  reeei\ed  consideration 
liy  tiie  Zinc  Corporation  for  the  year  or  two  preceding  the  European 
war.  Lyster's  process  is  carried  on  in  neutral  or  alkaline  solutions 
(never  acid)  of  the  sulphates,  chlorides,  or  nitrates  of  calcium, 
magnesium,  sodium,  potassium,  or  of  their  mixtures,  or  solutions 
of  manganese,  zinc,  iron,  acid  sodium,  or  sodium-potas-sium  sulphates. 
I'sing  eucalyptus  oil  or  a  similar  frothing  agent,  the  agitation  of  the 
pulp  takes  place  in  centrifugal  pumps,  throttled  to  give  further 
agitation,  and  discharging  i  :o  spit/.kasten  with  constricted  tops. 
It  is  s<iid  tiiat  a  galena  froth  can  he  collected  carrying  5,")  to  GO',' 
lead  and  that  hy  sending  the  tailing  to  a  second  machine  with 
furtiur  addition  of  oil,  iiie  s|)|ialerite  can  he  floated. 

It  will  he  noticed  that  this,  with  tiie  pos-sihle  exceptioji  of  Went- 
wortli's  sceoiul  patent,  is  one  of  the  first  ])roposals  to  give  a  true 
■preferential'  ■lotation  to  a  mixturi!  of  sulphides,  as  the  roasting 
iiietiiods  ahove  mentioned  involve  an  actual  conversion  of  some  of 
the  minerals,  so  that  sulphide  surfaces  are  no  longer  presented  to  the 
oils  and  air  liuhhies  in  the  flotation  operauo'i.  Lyster's  process, 
however,  involves  the  actual  flotation  of  one  mineral  in  preference 
to  another,  unless  the  eliemicals  used  are  chemically  altering  certain 
of  the  sulphides  so  that  they  cannot  float.  Anyone  who  has  worked 
with  mixtures  of  sulphides  has  douhtless  noticed  that  greater  care 
is  necessarj  in  the  flotation  of  zinc  sulphide  than  in  floating  galena: 
in  fact,  galena  is  one  oi  the  most  easily  floated  minerals  outside  of 
molyhdenite,  and  zinc  sulphide  is  considerahly  more  diffieult.  The 
fact  that  a  froih  running  so  high  in  h'ad  as  the  Lyster  process  is 
reported  to  give  would  also  tend  to  make  one  suspicious  that  rather 
poor  flotation  conditions  are  maintained,  so  that  only  the  most  easily 
floated  material  (galenal.  and  only  the  purest  of  that,  is  coming 
up  in  the  first  product.  This  tnkes  place  t'ven  ii-  the  presence  of 
considerahle  oil,  whenever  flotation  condition.^  ar.'  poor  on  almost 
any  type  of  machine,  and  while  the  grade  of  froth  that  is  obtained 
is  high,  the  extraction  is  poor  on  account  of  the  fact  that  only  the 
l)est  mineral  is  floating.  Tf  is  |)o.s.silile  that  some  such  combination 
of  results  as  this  has  caused  the  process  not  to  h  ■  considered 
unfavorahlv. 


I 


(I 


78 


THE    FLOTATION    PROCESS 


NiTThn  AMI  LwKKs.  I'l'iliaps  tlif  iiiost  iiiiportaiit  disclosiiri.'  of 
H  pnn'i'ss  for  iti-ffcrt'iitial  flotation  of  iiiiiifrals  is  contained  in  tlic 
patent  specitications  taken  out  liy  K.  II.  Nutter  and  II.  Lavers. 
r.  S.  Patent  Xo.  1,067,485  of  ]!»!:!.  This  i)atent  was  assigned  to 
Mineiul.-i  Separation,  Limited,  us  tlic  patciiu.es  are  engineers  in  the 
employ  of  tiiat  eomi)a!iy,  Tiie  wonling  of  the  patent  shows  more 
actual  contact  with  flotation  work  on  the  part  of  the  patentees  than 
|irrha|)s  any  otlier  si  ^Me  patent  tliat  lias  heen  granted.  They  have 
ohserved  that  while  controlling  conditions  in  a  flotation  plant,  the 
varying  of  certain  of  these  conditions  has  been  accompanied  by 
eiiaiiges  in  the  character  of  the  froth  coming  off  their  machines, 
the  metals  coming  oft'  in  various  r-Uios  to  each  other  at  different 
times,  and  for  detinite  causes.  Thus  there  is  considerable  dift'erenee 
ill  the  sizes  of  the  different  minerals  s<'parated  under  various 
conditions.  It  is  no  uiieonniion  experience  while  developing  the 
machinery  of  a  flotation  mill  to  float  all  of  the  flne  part  of  the 
gaiiguc  as  well  as  the  .sulphide  minerals.  In  like  manner,  the  more 
easily  flotative  minerals  are  liable  to  come  off  in  the  first  froth  that 
i.ssiies  from  a  machine  ai'companied  by  the  more  finely  divided 
portions  of  the  less  easily  flotative  minerals.  "This  tendency  is 
deiieiident  upon  several  faetoi-s,  .such  as  the  amount  a  ..1  character 
of  the  agitation  and  aeration,  or  of  each  singly,  the  chemical 
coiistituti<iii  of  the  solution  en.ploycd  as  mill-wrter.  the  degree  of 
dilution,  the  temperature  and  the  amount  and  natun  of  the  diffc  •ent 
fn)tliing  agents."  '•The  word  aeration  is  used  in  this  specification 
to  mean  the  supplying  of  air  or  other  i.'.!Ui  or  gase^."  By  siifiicicntly 
controlling  all  of  these  factors  it  is  possible  to  obfpin  effective 
separation  of  galena  and  sphalerite  as  well  as  other  sulphid  >s  and 
metals.  By  taking  the  various  froths  obtained  from  subjecting  the 
pulp  to  varying  conditions,  and  cliussifying  on  apparatus  such  as 
concentrating  tables  it  is  often  possible  to  get  good  separation  of 
the  minerals  contained. 

One  example  cited  is  that  of  an  ore  containing  sulphides  of  ie'id. 
copper,  and  /.inc.  From  this  <an  be  obtained  a  froth  ce.ntaini.ig 
most  of  the  dialcopyrite.  and  not  much  of  the  galenn  or  the  sphalerite, 
by  the  use  of  cresylie  acid  fcresol")  without  the  addition  of  mineral 
ai-id  to  the  pulp.  This  froth  can  be  re-treated  under  varying  con- 
ditions to  purify  it.  To  thi'  mill-pulp  that  has  been  deple.ed  of  its 
cop])er  can  be  added  sulphurii'  acid  as  well  as  the  frothing  agent, 
to  obtain  the  major  portion  of  the  lead.  and.  finally,  by  the  addition 
of  such  an  oil  as  oleic,  it  is  ixissiV.le  to  float  all  of  the  zinc  mineral. 


PREFERENTIAI.    FLOTATION 


79 


as  well  as  any  coarse  particles  of  chalcopyrite  aud  galena.  The 
re-treatment  of  these  froths  by  further  flotation,  or  on  tables,  makes 
it  possible  to  get  good  products  of  the  grade  demanded  by  smelters. 

Wlien  using  an  ore  containing  only  copper  and  zinc  sulphides 
they  state  that  with  the  use  of  cresylic  acid  or  eucalyptus  oil,  without 
the  addition  of  any  mineral  acid,  it  is  possible  to  get  a  froth 
containing  a  portion  of  the  copper  minerals,  some  fine  zinc,  and 
some  still  finer  gangue.  Tiiey  also  state  that  if  the  remaining  pulp 
is  acid,  the  froth  obtained  will  contain  an  additional  amount  of 
more  coarse  zinc  and  copper  minerals  and  that  the  zinc  minerals 
are  finer  than  the  copper  minerals.  If  oleic  acid  is  added  to  clean 
tlio  tailing,  the  frotii  obtained  will  carry  much  gangue,  but  most 
(if  the  sphalerite  and  chalcopyrite  are  very  coarse-grained.  The 
treatment  of  these  froths  on  vanning  machines  or  tables  gives  the 
desired  products. 

Consciously  or  unconsciously,  a  number  of  operators  have  applied 
methods  more  or  less  like  those  claimed  in  this  patent.  By  restricting 
the  aiiiou!>t  of  oil  u.sed.  it  seems  to  be  possible  to  float  galena  in  the 
presence  of  sphalerite,  though  the  lead  product  obtained  always 
carries  a  good  deal  of  zinc,  and  it  is  impossible  to  get  all  of  the 
lead  out  before  the  sphalerite  is  flja+ed  by  the  addition  of  further 
oil.  This  is  practically  an  application  of  Lyster's  process,  except 
that  pure  water  is  used  instead  of  the  solutions  recommended  by 
him.  However,  there  can  be  no  doubt  that  'he  addition  of  certain 
substances  to  the  mill-water  does  help  in  this  type  of  flotation. 
In  another  phm'  where  an  ore  containing  pyrite  and  chalcopyrite 
is  being  treated,  the  first  froth  contains  most  of  the  chalcopyrite  in 
a  finely  divided  form,  while  only  a  small  amount  of  the  pyrite,  m 
large  pieces,  comes  to  tlie  surface.  The  property  of  chalcopyrite 
to  disintegrate  into  very  fine  flakes  on  crushing  has  bothered  mill- 
mer.  in  the  old  days  when  the-  pro  luctiou  of  slime  was  kept  down 
to  a  minimum.  Now  it  seems  to  be  an  advantage.  These  two 
instances  of  "controlling  flotation"  conditions  are  somewhat  different 
from  the  ones  implied  in  the  Nutter  and  Lavers  patent,  and  it  is 
doubtful  if  it  could  be  helrt  to  cover  these  cases,  at  least  more  than 
iii  part.  However,  too  much  attention  cannot  be  given  to  their 
)ateiit,  as  it  discloses  the  methods  by  whicti  preferential  flotation 
•  ill  be  first  developed  successfully,  as  far  as  I  n-ii  able  to  see. 

Grkh.nwat  and  Lowry.  a  further  develop.nent  of  the  idea  of 
using  a  solution  of  some  ci-imical  that  will  permit  true  preferential 
flotation  of  one  mineral  in  the  presenct'  of  another  flotative  mineral 


80 


THE    FLOTATION    l'l!()(K>: 


is  (-(.titaiiird  ill  tlic  pat.iit  of  II.  H.  (Iivniway  aii.l  A.  II  1'.  Luwiy, 
No.  1,1U'J,7:{.S  of  11(14.  Tliey  disoov.-inl  tliat  "if  a  salt  of  fhroinimu 
(such  as  sodimii  liicliroiiiatf  or  i)()tas.siiiiii  hiclinuiiate)  is  iiitrotluoed 
ill  solution  into  tlio  fin-uit  li<|uors,  or  if  tlu'  niatfi-ial  to  In-  tivatt-d 
is  subjected  to  tile  action  of  sueli  cluoiuiiiMi  s<ilt  solution  liy  digestion 
or  otherwise,  the  sulphides  are  affected  in  such  a  way  as  to 
leave  certain  of  them  aiiienuiile  to  flotation,  whereby  products  arc 
obtained  relatively  lii^'li  in  certain  suli)hides  on  the  one  hand,  and 
relatively  hif,'ii  in  the  other  siili>hides  on  the  other." 

Three  examples  are  cited:  (1)  A  luolybdenum  ore  coiitainini.' 
1.')%  molybdenite  and  2o',[.  iron  pyrite  was  crusheil  to  pas-s  lOO-niesh 
screen  and  treated  in  a  froth-tlotation  apparatus  with  four  times 
its  weight  of  water  <-ontainiiii,'  0.2')' l  sodium  bichromate,  and  heated 
to  120  F.  One  pcmnd  of  eucalyi)tus  oil  per  ton  of  slime  was 
used  and  tiie  Hotation  product  consisted  of  !>:{',t  MoS_,  and  4.!)'; 
iron  pyrite.  Attention  should  be  called  to  the  fact  that  this  example 
docs  not  tell  as  imich  as  it  would  seem  to  say.  for  the  reason  tliat 
molybdenite  is  one  of  the  nu/st  easily  fionted  min.'rals.  I  believe 
that  work  of  a  charai-ter  more  nearly  comparable  with  this  result 
could  be  obtained  witiiout  the  use  of  ehroniates. 

The  si'cond  cxami)le  cited  is  of  a  co]>per  ore  containing;  <>.■>'. 
copper  and  :jr)';i  iron.  This,  likewise,  was  crushed  to  pass  a  100-mesh 
screen  and  digested  in  a  hot  sohuion  of  1%  sodium  cliromate  for 
about  :{()  minutes,  the  liquor  decanted  and  the  mineral  treated  in 
a  notation  machine  with  one  pound  of  eucalyptus  oil  per  ton  of 
dry  slime.  The  flotation  product  contained  19%  copper  an.i  W:!' } 
irmi,  while  the  residue  contained  O.TVo  copper  and  -K.'Z^/c  iron.  When 
we  'rememl)er  the  ca.se  cited  above  of  s<>parating  the  chalcopyrite 
from  the  pyrite  liy  virtue  of  the  fact  that  fine  grinding  takes  the 
copper  down  to  a  much  finer  i)roduct  than  it  does  the  iron,  we 
are  1.<1  to  wonder  if  this  i>roeess  is  really  necessary  for  this  kiiul 
of  ore  It  may  be  that  a  better  gra.b-  of  product  and  a  higher 
extration  can  be  obtained  by  this  method  than  witl'out  the  a.ldition 
of  bichnunate.  but  otherwise  it  is  doubtless  possible  in  most  cas(^s 
to  do  the  same  work  willi  proper  control  of  onlinary  coiulitions. 

Tl'.eir  third  exami)le  is  of  a  lead-zinc  slime  containing  IS.*')','  lead 
and  IS'i.I^-:,  zinc,  which  was  digested  for  30  minutes  in  a  warm  soluthui 
of  1^;  s<idium  bichromate.  The  solution  was  decanted  and  tiu- 
material  subjected  to  froth  flotation  with  one  pound  of  eucalyptus 
oil  per  ton  of  slime.  Tlie  flotation  product  eoiitain<>d  47.2%  zinc 
and   G';;    lead,   while   the   residue   contained   :n.6%    lea.l   and    Ifi.lJ^, 


IKKKKKKNTIAI,    KI.U'IATK  l.\ 


81 


/inc.  Tln'  solution  was  licahd  to  120'  ('.  These  are  iuterestiug 
lij-'iiies.  lint  tliere  is  too  tinirli  /.ine  in  tlie  leacl  eoiicentrate.  Here 
again  I  feel  that  the  work  is  not  nineli  better  tlum  it  would  be 
without  the  aid  of  biehroniates.  Hy  taking  advantage  of  the  fact 
that  galena  floats  more  easily  than  blende,  it  is  possible  to  get  a 
galena  froth  from  an  ore  that  will  contain  54',;  lead  and  15% 
zinc,  while  the  blende-frotii  that  follows  will  contain  37%  zinc  and 
20%  lead.  This  type  of  work  eri-s  in  the  other  direction,  that  is, 
in  liavi!ig  too  nnn-h  lead  in  the  zinc  product,  but  the  point  is  that 
the  addition  of  bieluomates  does  not  make  a  .separation  which  is 
any  more  advantageous  than  does  preferential  flotation  by  other 
methods.  However,  the  fact  that  the  galena  can  be  deadened  by 
treannent  with  a  weak  solution  of  sodium  bichromate  is  most 
interesting  in  that  it  shows  that  a  true  preferential  flotatio'i  is 
possible.  It  is  a.ssumcd  that  the  action  of  the  bichromate  solution 
iuu.st  be  that  of  oxidation  of  the  surfaces  of  the  galcn-.  to  in.soluble 
sulphate,  while  such  an  action  on  the  sphalerite  emdd  not  be  possible, 
as  the  zinc  sulphate  would  dissolve.  The  ♦reatment  of  the  high 
lead-zinc  product  of  this  last  mentioned  preferential  flotation  product 
by  the  bichromate  process  might  be  a  useful  method  of  cleaning  this 
kind  of  concentrate.  It  is  probalile  that  successful  preferential 
flotation  will  develop  along  such  lines,  though  bichromates  are  not 
the  only  chemicals  that  will  be  used.  AVliih.  the  results  obtained 
by  this  process  have  been  shown  to  be  cj.pable  of  duplication  other- 
wise than  by  the  ui-e  of  bichromates,  this  fact  of  the  jjeculiar  m. tion 
of  weak  l)ichromate  solutions  is  thankfully  accepted  and  further  worl: 
is  urged  to  discover  if  it  I'an  have  a  field  of  application  p"culiarly 
its  own. 

Br-\dford.  Another  process  along  these  lines  is  that  revealed  in 
British  Patent  No.  21,104  of  19l;<,  by  L.  Bradford  .>f  Broken  Hill. 
He  chiims  the  use  of  solution  that  will  wet  one  of  the  sulphides 
wiiich  it  is  desired  to  separate  from  the  other  preferentially  without 
I'heinically  altering  the  same.  A  medium  which  will  wet  galena 
particles  and  allow  splialerite  and  pyrite  to  float  unafTected  is  a 
solution  of  one  or  more  of  the  alkaline  chlorides,  slightly  acidulated 
and  heated  to  about  120  to  160°  F.  On  account  of  its  low  cost  a 
solution  of  sodium  chloride  is  used,  and  Bradford  .states  that  there 
are  no  definite  requirements  as  to  how  concentrated  the  solution  shall 
be.  but  suggests  a  10','  NaCl  solution  as  about  the  right  strength 
to  tise. 

The  acidity  should   be  about  0.1   to  0.2%,   for  a  higher  am(,unt 


THE    1I.OTATION    I'KOCKS.S 


than  l^r  will  cinisc  tin'  floliilioii  nf  siiilcna  on  npoount  of  tin' 
fornialion  of  liydroirrii  siii|)liiili'  hiitililcs  on  its  surl'afc.  He  states 
that,  it'  till'  i)niitss  i>s  aippliftl  dii'iM-tly  tn  crudt^  ores  the  use  of  a 
i'rothiDjr  a^tnt  is  not  niTcssary.  aitlioii^'li  it  will  cause  no  harm  it' 
added.     Any  well-known  M|»paratiis  ean  be  used  for  the  Hotalion. 

The  invention  may  he  appliid  either  to  the  erude  ore  or  to  the 
mixed  flotation  coneentrate  from  the  ordinary  method  of  flotation. 
^VIlere  the  plant  is  useil  on  erude  ore  the  tailin-^s  from  the  flotation 
of  the  sphalerite  and  the  ]>yrite  are  agitated  again  lu  pure  water 
with  a  frotliin-;  aireiit  in  order  to  float  the  galena.  On  aeeount  of 
this  requirement  it  is  thought  better  to  make  a  mixed  coneentrate 
first  by  ordinary  flc»tation  and  then  separate  preferentially  as  above 
described.  Tliis  latter  method,  however,  makes  a  higher-grade  /ine 
concentrate. 

When  treating  ordinary  mixed  flotation  concentrate,  it  is  best 
to  remove  the  oil  on  the  surface  by  the  use  of  au  alkaline  or  an 
alkaline  carbonate  solution,  or  by  either.  Further,  finelv  ground 
material  is  liable  to  agglomerate  too  quiekly,  so  that  some  of  the 
galena  will  be  entrained  mechanically  with  the  agglomerated 
sphalerite  and  decrease  its  value.  In  tiicse  cases  it  is  desirable  to 
add  iin  agent  that  will  retard  tlotation.  Substances  suital)le  for 
this  purpose  arc  >ulpiiitcs  or  tliiosulphitcs  of  alkidies  or  sulphur 
dioxide,  but  they  must  be  used  sparingly  and  with  care,  or  they 
will  entirely  spoil  all  flotation.  He  thought  so  nuidi  of  this  latter 
step  that  he  later  incorporated  it  in  a  scj)arate  jjatent  (Brit.  I'at. 
No.  1!1.844  of  1014.)  No  further  (les<;ription  of  this  patent  is 
necessary. 

There  arc  many  other  proposed  methods  in  the  ])atent  literature 
of  Hnglaiul.  (!e.  many.  France,  and  the  Fnited  States,  concerning 
wliich  I  am  not  fully  informed,  but  it  is  believed  that  most  of 
the  important  iiies  have  been  reviewed.  Many  interesting  details  are 
disclosed,  sucii  as  the  fact  that  galena  and  sphalerite  will  not  float 
in  a  solution  containing  zinc  chloride  of  the  right  concentration  and 
aciditicd  by  hydrochloric  acid  ((ierman  jtatent,  Np„  282,2;U).  Aniline 
eomi)ounds  aic  sai.l  to  allow  flotation  of  galena  in  preference  to 
sphalerite,  etc. 

It  will  doubtless  be  noticed  that  little  mention  is  made  of  the 
kinds  of  machinery  used  in  the  above  methods  of  i)referential  flotation 
and  there  will  do\ibtless  be  some  question  as  to  whether  or  not  these 
principles  can  1h^  applied  equally  well  in  the  mechanically-agitated 
and  in  the  i)neumatic-agitation  machines.    Most  of  the  above  processes. 


.I-.-p-'-- 


ri.or  vrid.N  at  tiik  inspikation  mink,  akizona  88 

wiiiic  liiit  spcciliiiilly  stat<'il,  have  Itceu  worked  out  witli  tli(>  aid  of 
iiiii-haiiicidly-afritatcd  iiiacliiiics,  lint  it  is  possihle  to  ai)ply  most 
of  iliiiii  to  tlie  pciiuniatieally-asitiited  rnacliincs.  stirli  as  the  Callow 
or  till'  Touiie.  Siieli  maehines,  owing  to  tlie  economy  of  power  in 
inakiiii;  fmth,  and  the  easy  control  of  flotation  eon(]itions,  will 
ciiiulitlcss  iiiateiiMlly  .issist  in  the  (li'\rlopinent  of  preferential 
rtotatimi. 


FLOTATION  AT  THE  INSPIRATION  MINE,  ARIZONA 
By  William  Motherwell 

(From  the  Milling  and  Scientific  Press  of  July  3,  1915) 

Tiie  Inspiration  Cousoliilated  Copper  Co. 's  mine  near  Miami,  in 
Arizona,  is  estimated  to  contain  i)7,l-l;3,U()0  tons  of  1.63%  copper 
or^,  mostly  in  the  form  of  ehaleocite.  The  ore  at  present  being  mined 
contains  about  0.20%  metal  in  the  form  of  Ciabonate  and  silicate. 

For  .S(  me  time  past  the  company  has  been  experimenting  witli 
a  view  to  finding  the  best  method  of  concentrating  the  sulphide  ore 
before  sivielting.  The  fii-st  test-mill  consisted  of  two  sets  of  rolls, 
oi  Chilean  mill,  one  llardinge  conical  mill  Z  ft.  diam.  by  12  in. 
cylinder,  Richards  hindered-settling  classifier,  Deister  tables,  some 
kind  of  vanner,  and  a  50-ton  Minerals  Separation  flotation  machine 
of  standard  tyi)e  (Hoover's  single-level  apparatus).  This  mill  was 
situated  close  to  the  Joe  Bush  shaft,  on  top  of  the  orebody,  ana  is 
now  dismantled.    It  is  understood  that  good  results  were  obtained. 

On  a  change  of  uianagement  taking  place,  a  new  test-mill  was 
erected  near  the  old  leaching  plant  of  the  Black  Warrior  Copper  Co., 
about  H  miles  from  the  new  twin-shafts  through  which  all  ore  will 
be  hoisted  wlien  the  lai'gc  mill  is  running.  This  mill  will  be  the 
largest,  or  rather  will  handle  the  largest  tonnage,  of  anj'  mill  in 
the  world,  namely.  ir),000  tons  per  day.  It  adjoins  the  test-mill 
as  can  be  seen  in  the  photograph  published  in  the  Mining  and  Scien- 
tific Pnss  of  May  20.  The  crushing  and  concentrating  capacity 
of  the  test-mill  is  about  1000  tons  i)cr  day.  but  it  is  limited  by  the 
capacity  of  the  classifiers,  elevators,  etc. 

The  ore  is  at  present  hoisted  tl  "ough  the  Scorpion  shaft  a!id 
broken  in  a  'K'  Gates  crusher  close  to  the  shaft.  From  there  it  is 
conveyed    to    the    30.000-ton    flat-bottomed    steel    and   concri'te   b.ins 


84 


IIIK    I'l.OlATIiiN    l'K(P(  K- 


nttiifhcd  to  the  cnislur-statiDii  iit  llic  new  slial'ts.  It  is  tln-ii  tiaiis- 
Idirti'd  tci  llic  tistniill  in  liipildshy  (liiiiip  lars  cacli  liavinn  a 
cjipacity  of  (JO  tons  driiun  liy  steam  loi'oinotivcs  on  a  staiidardt^autJc 
railway.  A  ])art  ot'  the  iifw  inill-hins  i  wliidi  arr  of  slci-l  and  tiMU^li- 
sliapi'd)  is  set  aside  for  tlie  use  of  the  test  mill.  On  leaviufj;  these 
bins  the  ore  falls  upon  a  t ray-eon vyor.  thi'n  to  an  inclined  ruhher- 
lielt  conveyor,  where  it  is  auloniatically  weifjhed.  At  the  heail  of 
this  conveyor  there  is  a  iiiaKin'tic  pwlley  that  removes  pieces  of 
iron  and  steel  which  may  have  f,'ot  nii.xed  with  the  ore.  At  this 
jMiint    tiiere   is  a  trriz/.ly  and   a  ;i()-in.   Syiiions  vertical-disc  cnisher. 

From  licrc  an  imdinc-eonveyor  carries  the  ore  to  the  top  of  the 
test-mill,  where  it  is  divided  into  two  streams,  one  f?oing  to  a  shakiii^i 
s<>rcen  from  which  the  oversi/e  falls  into  a  4S-in.  Symons  iiori/.<'ntal- 
disc  crusher,  where  it  is  crushed  dry,  and  the  other  to  a  .')  ft.  (j  in. 
liy  S  ft.  diani.  Marcy  liall-mill,  where  it  is  crushed  wet  without 
previous  st'reeiii-  '.  The  product  of  tli  Symons  machini'  is  fed 
to  pebhlc-niills  without  any  ela.s.s:ticatioii,  heinf:  distril)ute(l  in  varying 
proportions  by  a  mechanical  device.  This  consists  of  a  lixed  hori- 
zontal circular  vess(M  lO.'i  inches  in  circumference  divided  into  four 
sections  liy  vertical  sheet-iron  partitions  that  can  be  ad.justcil  to 
</\\c  sepmcnts  of  any  size,  thus  varyitip  the  feed  to  eadi  mill  as 
desired.  By  measuring  the  numiier  of  indies  of  eireumference  jrivcn 
to  each  division  the  proportion  of  feed  poinfr  to  each  null  can  be 
calculated.  Above  this  receptacle  there  is  a  vertical  crooked  revolviuf? 
iron  |)ipe  through  wliic-li  the  feed  comes  from  tlie  Symons  machine 
after  ]>ein<r  mixed  with  water.  The  revolution  of  the  feed  ])ipe  causes 
the  ]tulp  to  lie  disdiarged  into  each  d..ision  of  the  distributor  in 
turn.  In  the  bottom  of  each  division  is  a  hole  through  wliicji  the 
f  ed  pas,scs  to  launders  leading  to  the  pel)ble-inills. 

T'le  following  kinds  of  pebble  mills  are  installc<l: 

1,  One  20  by  fi-ft.  Chalmers  &  ^Villiams  (luick-dischargc  tube- 
mill  with  licrring-botie  gear  engatring  with  fiinion  on  a  shnft  directly 
driven  through  a  flexible  coupling  by  an  electric  motor. 

2.  One  llardinge  conical  mill.  H)  ft.  diam..  with  cylindrical  i>art 
23  in.  long  driven  through  spur  and  pinion  by  two  idt  transmission 
from  motor. 

:!  One  llardinge  conical  mill,  8  ft,  diam.,  with  cylinder  72  in. 
long,  with  herring-bou"  gear  engaging  with  pinion  on  shaft  direct 
driven  by  motor. 

4.  One  llardinge  conic;.l  mill.  8  ft,  diam,.  with  cylinder  :!ti  in. 
long,  driven  in  the  same  manner  as  No.  '-V 


rr,iiT\iiii.N    \T  Tin:  in>i'IU\i  ion  mink,   vki/.onx 


85 


"i  Oiii'  Hiinlin^c  ((iiiical  mill.  M  It.  (iiiiiii..  with  cyliiulcr  44  in. 
loiip,   driven   ill   siiiin'   way  jus  Xd.   it  and  4. 

Hotli  .sik'x  and  Kl  Oro  iiiiiii(is  wore  tried  in  the  I'vlindrieal  part, 
and  [leliMcs  vet  in  eenient  in  the  ecuiieal  p;irt  ;  and,  in  nne  mill, 
.steel  i)lates.  wliieli,  iiiA>.ver,  did  not  la.st  lonjj. 

Each  pchljle-mill  h.is  a  dra>r-<da.s.sitier  attached,  and  the  oversi/e 
in  the  product,  except  in  the  eii.=e  of  the  tiihcniill.  is  returned  hy  a 
l)ucket-elcvator  to  the  mill  from  whii'li  it  came.  In  the  ea.s<>  of 
the  tiilie-mill  the  oversize  is  retmiii'd  to  the  mill  hy  the  dratj-chussitier, 
which  is  paralled  with  the  mill.  Hoth  Danish  and  California  pehhles 
have  hccn  tried. 

The  product  of  the  Jfarcy  hall-mill  is  classified  in  a  duplex  Dorr 
classifier,  and  the  oversize  returned  to  thi-  same  machine.  This. 
a.s  a  tine  crusher,  has  a  capacity  of  ahout  l:}  tons  per  hour.  Of 
the  final  product  only  ahout  I'}',  remains  on  a  4H-mcsh  screen.  The  mill 
is  simply  a  strongly  hiiilt  cylinder  supported  on  trunnions,  contains 
ahout  10  tons  of  chrome-steel  or  manganoid  halls,  and  is  revolved 
at  22  r.]).m.  It  was  formerly  fe<l  thi-ouRh  the  trunnion,  then  three 
scoops  were  att.iched.  hut  now  one  larfre  .scoop  is  used.  It  is  lined 
with  inanganes«'-steel  plates  and  driven  thmuph  spur  and  pini-)n 
hy  heltiiifj  from  a  200-hp.  motor,  usiiifj  ahout  140  kilowati.s.  The 
discharge  is  at  the  opposite  end  to  the  feed-inlet  and  pa.ssos  through 
grates  composed  of  ste"!  hars  placed  close  together.  The  discharge 
area  is  more  than  half  the  entire  end  of  the  mill.  It  will  thus  he 
seen  that  •'  ditTei-s  es.sciitially  from  the  Krupp  hall-mill,  in  which 
the  screens  are  placed  around  the  periphery  and  the  pulp  has  to 
piLss  through  two  screens  hefore  escaping.  The  pulp  leaving  the 
hall-mill  contains  ahout  40'';  of  moisture.  This  is  diluted  hefore 
entering  the  Dorr  classifier.  The  overflow  from  the  classifier  consists 
of  2.^  to  :!  parts  of  water  to  one  of  ore. 

The  power  required  to  drive  these  ditTcrent  mills,  their  capacity, 
consumption  of  balls,  pehhles,  and  liners  are,  of  course,  known  only 
to  the  management,  hut  it  is  significant  that  in  the  new  mill  all 
crushing  will  he  done  hy  llarcy  mills. 

Among  other  eru..iiing  machines  that  have  hee.n  tried  are  the 
Hradley  roller-n.ill,  Symons  roUer-inill,  Ovcrstrom  mill,  and  Allis- 
('lialm"rs  hammer-mill.  \o  i*olls  or  Chilean  mills.  Krupp  mills,  or 
Marathon  mills  were  tried  in  this  plant. 

The  j)roducts  of  the  Marcy  mill,  and  such  of  the  pehlile-mills  as 
are  running,  are  united  and  elevated  sut>iciently  high  to  flow  to  all 
the   flotation   plants   without   undergoing   any   preliminary   tahle   or 


86 


TUK    FIOTATIDN    I'KdCKSS 


vaiiiit'i'  idiicfritralKiii.  'I'lii'  tVi'il  is  distrilditcil  in  Ilic  Hotiition  plaiitN 
in  tlu'  l'i)lli)uiiii:  way  :  It  Hows  into  the  (•cntrr  of  a  liori/ontal,  circular, 
rcvolviiijr  ai>[>araliis  ot'  slicci  iron  divided  iiitn  five  concentric  circles 
or  ring's.     Hadi  circle  lias  20  holes  in  the  liottoni.  and  the  pn)p()rtio!i 

of  I" 1   to  each   flotation   |>lant  is  rcpridated   hy   openin>{  the   proper 

iiuniher  of  holes  and  allowing  the  pulp  to  enter  a  launder  alontf 
which  it  flows  to  the  flotation  plant.  Thus  if  the  ririR  that  receives 
the  fet'd  intended  for  one  parficulnr  plant  has  15  holes  plupped  and 
.">  open,  this  plant  is,  of  coins*',  receiving  2ij^,'  of  the  total  feed,  and 
the  actual  tonnage  passed    lirouRh  it  can  be  calculated. 

.\iitoiiiatic  samplers,  worked  tiy  a  water  halnnce.  are  use<l  through- 
out the  mill.  All  assays  are  done  hy  the  electrolytic  method,  usinn 
rotatinjr  anodes. 

.Most  of  the  flotation  •oil'  is  added  to  the  pul|)  at  the  head  of 
the  mill,  licinjr  fed  from  a  tank  hy  a  small  bucket-elevator  driven 
by  a  shaft  havintr  a  cone-step  p\illey,  so  that  the  speed  of  the 
elevator  and  the  (piantity  of  "oil'  can  be  varied  to  suit  the  tonnatte 
of  ore  l)ein^  crusheil.  This  is  much  more  satisfactory  than  lettiuR 
the  'oil'  drip  from  a  can.  Any  additional  reagent  that  may  be 
reipiired  is  added  at  each  flotation  i)lant  by  dripping  from  a  can. 

The    followinfr   methods  of   flotation   have   been    tried: 

1.  An  8-coinpartnient  Minerals  Separation  machine  of  stamlard 
type  (as  described  in  Hoover's  book  on  flotation'*,  having  a  nominal 
capacity  of  fiOO  tons  per  day.  The  agitation  compartments  are  ;]  ft. 
square,  and  the  flotation  coini)artinents  or  spitzka.sten,  5  by  :!  ft.  The 
spindles  are  driven  flirou>rh  enclosed  bevel-gearing  by  a  pulley  on 
a  hoii/ontal  shaft.  The  overflow  from  tiie  first  si.x  compartments 
\V!us  sent  to  the  concentrate-bins  without  'cleaning'  or  further  treat- 
ment designed  to  raise  the  grade  by  I'liminating  insoluble  matter 
anil  the  ovi'i'tlow  from  the  last  two  i'omi)artments  was  returned  to 
the  li(>ad  of  the   machine.      This  machine  was  discarded. 

2  .\  12-compartmcnt  Minerals  Separation  machine  of  standard 
type,  of  the  same  cai)acity  and  driven  in  the  same  manner  as  \o.  1, 
the  a<lditi()iial  compartments  being  intended  to  j)rolong  the  treat- 
ment. At  fii'st  the  conc(Mitrate  and  middling  were  dealt  with  as 
in  No.  1  machine.  l)Ut  afterward  the  overflow  from  all  compartments 
was  'cleaned'  in    (:!'.  liexl   dcscriheil. 

:!  All  ^compartment  "lO-ton  Minerals  Seiiai-ation  machine  of 
slaiKJani  type,  the  spiiellcs  beiiii.'  driven  by  half  i-rnsM^d  belts  from 
pulleys  on  a  horizontal  shaft.  The  ovcrflfiw  from  all  compartments 
was  sent  to  concentrate-bins,  and  the  tailing  was  refurncil  to  the  liead 


i 


''tmjmm^mmimm^Mm. 


■t^." 


HulMlliN     \T     I  UK    INS|'|K\TI(I\     VHSK,     \HI/UN\ 


of  No.  2  iiia'-tiini'.  This  concentrate  contuineiJ  atxml  :U)'i  copper. 
These  two  iiiiichineH  were  in  use  until  n-ceiitlj'. 

4.  An  Hcoinpiirlnifnt  Minerals  Separation  machine  of  new  type, 
known  JUS  a  "snh  aeration  inHcliine.'  Thi'  affitation  coinpartinenlH 
were  covere<l  on  top,  and  both  mechanical  ai;itati(>n  and  compressed 
air  were  u.s<>d.  The  agitation  compartments  contained  cast-iron 
Iiartle-|)late8  li.xed  to  the  sides,  and  the  im()ellers  were  ditTerent  from 
those  nsed  in  the  standard  machine,  hut  the  spindles  were  driven 
in  tlie  nsnal  way.  Tiie  dis<'liar>rc  from  the  agitation  compartments 
to  the  flotation  con.partments  was  IiIkIi  up.  Tiie  air  used  for  the 
Jieration  of  the  pulp  was  introduced  throupii  a  hole  in  the  Itottoni 
of  each  n>{itafion  compartmi-nt  at  a  pressure  of  al)out  2  Ih.  per  square 
ineli  It  ditl  not  pa.ss  tiirouKh  any  porous  medium.  Tiiis  machine 
had  the  usual  valves  and  suction-pipes  in  the  bottom,  hut  was  after- 
ward alten'd  to  (.'))  a  machine  of  I  he  Hehhard  type,  with  agitation 
gear  of  the  standard  Minerals  Separation  pattern,  hut  with  horizontal 
discs  in  place  of  the  usual  screw  impellers.  Kach  spindle  nuikes 
about  ;5tM)  r.p.in.  In  tiie  Ilebbard  iiuichine  as  us«'d  in  Australia 
the  agitators  are  driven  from  below.  There  are  no  spit/kfisteu,  the 
overflow  of  ('onccntrate-froth  taking  place  from  the  agitation  com- 
partments. ('oiise(piently  there  are  no  suction-pipes  and  valves  in 
the  bottom,  and  no  plugs  to  drav  and  re))lace  when  a  stoppjige  takes 
place.  The  wooden  |)artitions  between  the  agitation  compartments 
have  been  removed  and  cast-intu  baffle-plates  about  15  in.  high 
substituted.  Air  is  blown  through  eight  holes  in  the  Imttom  as  in 
Xo.  4  nuiehine  (des<'ribed  above)  and  water  under  pressure  is  used 
to  j)revent  pulp  from  entering  the  air-i)ipe.  On  a  feed  of  about 
.'KM)  tons  per  day  this  machine  has  given  good  results,  and  is  still  in 
use.  The  low-grade  'Miiiccntrate  made  by  this  machine  is  ■(■leane<r 
in  another  machine  of  standard  type. 

G.  A  Towne-Klinn  plant,  or  bubble-column  concentrator  with  a 
nominal  capacity  of  50  tons  per  day.  This  consisted  of  (1)  Pachuca 
agitator  in  which  the  pulp  was  mixed  with  oil,  (2)  a  cast-iron 
vertical  cylinder  with  a  bottom  of  carborundum.  The  oiled  pulp  is 
fed  into  the  top  of  the  cylinder  through  a  pii)e  that  delivers  it  below 
the  surface.  Air  at  a  pressure  of  5  lb.  per  square  inch  is  blown 
through  the  cai-b<>rinidum.  Hubbies  are  formed,  that  adhere  to  the 
oiled  sulphide  particles,  forming  a  froth  overflowing  at  the  top  nf 
the  cylinder  into  a  launder,  whence  it  flows  to  ('.])  a  similar  cylinder 
at  a  lower  level,  where  it  is  'cleaned.'  The  tailing  from  the  first 
cylinder  escapes  through   a  hole  in  the  middle  of  the  earborundnni 


i 


r-- 


1^1 , 


MICROCOPY    RESOLUTION    TEST    CHART 

ANSI  and  ISO  TEST   CHART  No     2 


1.0   "^K  m 


I.I 


I  2.2 
12.0 

1.8 


'•25    III  1.4     i  1.6 


j=     APPLIED  IN/MGE     Inc 


-a;p-.     'ttH     'O"  i*»t] 

I   *8,!  -  OJOO  -  Pnone 
288  -  59«9  -  ro» 


88 


THE    n.OTATIOX    TROrKSS 


atiil  Hows  tliniiiirli  ;i  j;iiom'-iicc1<  Ikisc  (  Iiv  which  the  wat.T-h  vd  in 
the  tii-Nt  ryliiiilcr  is  rcEfnialcd  t(i  i4i  aiiothiT  cyliniliT  wIhtu  it 
rcci'ivi's  similar  trcatinciit  ami  tiioi'c  coiicciitratr  ovcrtlows.  This 
coiicontrate  also  is  re-lrcatcd  in  the  saiiif  cyliiidcr  as  Iho  coucoiitratt' 
i'l'diii  tlu>  fii'st  cyliiidt'r.  and  tln'  tailinji  from  this  cylinder  or  ■cleaner' 
is  returned  to  the  I'achuea  a^'itator  at  the  t()]>  of  th(^  huildiin^  liy  a 
eeiiti-ifnf.'al  ]>iiinp.  The  ail'  is  fui-nished  hy  a  l{oots  tilouer.  'J'his 
plant  was  dismantled. 

7.  A  Callow  ])lant  eonsistiuf;  of  1 1  i  Paduica  ajritator  l.S  ft.  deep 
hy  4  in.  diam.,  i  "J  i  five  cells,  each  S.t  ft.  lon<x  by  2  ft.  wide,  witii 
nominal  eaiiaeity  of  50  tons  each  per  day,  (iii  one  cleaner-cell  12  in. 
wide.  f4i  one  air-compressor,  (oi  one  receiver,  ((ii  ( 'onnersville 
Mower  with  a  displacement  of  ;i.:i  en.  ft.  of  air  pvr  revolution,  I  7  i  two 
.■{-in.  ecntrifntral  pumps,   (Si   :50-hp.  motor. 

Mr.  Callow's  letter  in  the  Mining  ax'l  Sciciitijir  I'r<  ss  of  ^Fay  '20 
full.v  desei-ihes  his  process,  so  I  need  not  ^o  into  further  iiartieulars, 
except  to  say  that  during  the  i)ast  few  months  the  plant  has  heen  run 
without  the  Paehuea  af^itators;  but  this  is  by  no  means  advisable. 
This  jdant  has  been  running  for  al)out  nine  months  and  has  jriven 
better  results  than  an.v  other  that  has  l)een  tried  here.  Forty  of 
these  cells  are  l)eini;  installed  in  the  new  mill. 

8.  A  nuichine  invented  b.v  David  Cole,  of  ;\roren<'i,  Arizona,  ciui- 
sistinp;  of  rectaiifrnlar  sheet-iron  tanks  with  jiipes  laid  liori/.(mtally  in 
the  bottom.  The  upper  half  of  theS(>  pi])es  is  eompo.sed  of  carborun- 
dum, and  air  from  a  blow(>r  is  forced  throufih  them  with  the  same 
effect  as  in  the  Callow,  Towne-Flinn,  and  other  pneumatic  processes. 
Perforated  wrousriit-iron  ])ipes  wrapped  with  flannel  or  canvas  have 
also  been  used.  The  tailiufr  from  the  tii'st  tank  is  re-treated,  ami  the 
eonceiitrate  from  all  tanks  is  re-treated  in  a  'cleaner.'  This  plant  is 
still  runninfr.  A  siTuilar  machine  is  in  use  at  ilorenci.  and  one  is 
beinp:  built  at  Cananea,  Sonora. 

n.  The  company's  metallni'jrist  has  devised  an  apparatus  intended 
to  combine  the  best  points  of  the  other  maehines,  but  without  infrin;?- 
inij  on  an.v  patents.  exce()t  those  of  th(>  ^linerals  Separation  Amei'ican 
Syndicate,  from  whc)m  the  eom|)any  liolds  a  licens(>.  Tt  is  called  the 
lns]>iratiiin  machine.  ,\t  tirst  it  resi'udiled  a  Callow  api)atatus  with 
an  almost  Hal  bollom.  Ilie  air  beiu'r  blown  through  <'anvas,  but  the 
fi'oth  overflowed  at  one  side  ol'  the  cell  onl.v,  and  there  were  pai'ti- 
tions  uhicii,  however,  did  not  reach  the  bottom.  It  was  twice  as  Ion" 
!i«  the  0!'<ii!ui!'\'  ('allow  ciijj  The  first  *_'OMC(»nt>'ate  \\':is  re-treated  if! 
a  smallci'  machine  of  tiie  same  type,  and  the  tailing  from  this  machine 


1  I.DTATln.N    AT  Tllh:   INsniiATlON    mim:,   AKIZONA 


89 


was,  as  usual,  returned  to  tlie  '  roufzlier"  eell.  Keeently  otlier  jyoruus 
media  lor  t'alse  bottonis  have  been  tried.  'J'he  iimeliiiiu  is  still  in  the 
experimental  stage. 

Jt  will  thus  he  seen  that  the  e(imi)any  has  spared  neither  time  nor 
money  in  endeavoring  to  find  the  best  flotation  process.  The  test-mill 
has  been  working'  since  January  ]!l]4.  and  about  50  flowsheets  have 
been  tried.  In  the  laboratory  there  are  (i  small  flotation  maehines  ot' 
the  .Minerals  Separation  type  in  almost  constant  use. 

The  tailing  from  all  the  flotation  plants  is  run  over  tables,  those  in 
use  being  Wilfley,  Deistcr  ]\raeliine  Co.'=!  double-deck  simplex  sand 
eoneentrator,  Deister  Machine  Co.'s  four-deek  table,  Dei.ster  slime 
table,  and  Deister  Concentrator  Co.'s  double-deek  table.  At  one  time 
the  ore  was  concentrated  on  tables  before  g')ing  through  the  flotation 
process,  but  this  was  not  found  suitable  for  the  Minerals  Separation 
jirocess,  as  it  left  too  little  mineral  in  the  ore,  and  for  this  and  other 
reasons  it  was  discarded.  The  mineral  s;ived  on  the  tables  is  mostly 
pyrite.  The  2:!4  tables  in  the  new  mill  are  Deister  Machine  Co.'s 
double-deck  type,  the  same  as  u.sed  in  the  Miami  Copper  Co.'s  mill. 
No  tests  were  made  with  any  kind  of  vanner.  The  sand  and  slime 
were  run  over  the  same  tables  without  classifleation,  but  this  will  be 
altered  in  the  new  null. 

The  tailing  from  the  tables  flows  to  the  dam.  the  retaining-wall 
lieing  built  by  allowing  tlie  coarse  sand  to  escape  through  cones  or 
inverted  pyramids  attached  to  the  tailing-launder. 

The  concentrate  from  all  flotation  plants  and  the  tables,  contain- 
ing about  28%  copper,  IG^',  iron,  and  267o  insoluble  matt^M-,  goes  to 
a  drag-classifier.  From  there  the  coarse  concentrate  goes  direct  to  an 
Oliver  filter  and  the  fine  to  a  V-shaped  settling-tank,  thence  to  the 
filter.  The  concentrate,  after  filtering,  still  contains  a  good  deal  of 
moisture.  It  is  trammed  to  a  bin  adjoining  a  branch  of  the  standard- 
gauge  railway  and  loadeii  into  bottom-discharge  steel  cars  belonging 
to  the  International  Smelting  Co.  Formerly  it  was  sent  to  El  Paso. 
Te.xas. 

Water  for  the  mill  and  domestic  purposes  is  ol)tained  by  pumping 
from  wells  in  the  flat  country  about  three  miles  distant.  A  large 
concrete  reservoir  has  been  built  on  a  hill  near  the  mill.  Electric 
power  is  ol)tained  from  the  power-house  at  the  Roos'svelt  dam  about 
40  miles  distant,  belonging  to  the  U.  S.  Reclamation  Ser\'ice,  and  the 
service  is  fairly  .satisfactory.  The  Inspiration  company  has  an  in- 
i( Tc.si.  in  Tne  pov»er-ihni.v  at  ilie  Internaiionai  smelter  neai-by,  where, 
in   ca.se  of  emergency,  a  supply  of  electricity  can  be  generated  hy 


90 


THE    FL(.)TAI'ION    I'KOCESS 


stfiuii   lioin   \v;inI>-   lu'iit    rroiii   tlic   rcvrrlieratitrics  aiul    Iroiii  oil-liiL-d 
Stii'liiiL'  lioili'is. 

As  iiii>Mtionf(l  III  ill.' aiinnai  iTpnrl  nf  tli^' rompaiiy  la  siiiiiinary  of 


. f  , 


1  Jymo'^i  l/frTcj/ 


..d/L^A- 


-.^££2i 


u/ev 


^  * , « .        ' i -~i  '^- ; > 1 


\ 


-f 


I        I  ^^V£  C/ass///i^' 


\M,.r.-'}/, 


fa/tef/T^a^ 


1"^^ 


\Sm^rer\ 


FUl.     Iti.       nOWSlIKKT    OK    THE    INJil'IK.M  ION     .Mill..       THE    RO.\STI.N(,    HJRN.\CK    JOB 
CONCEMB.MK   IS    AT   THE    S.MELTEB    NEAB-BY. 


wliicli  appoarc-a  in  the  Minituj  and  Scientific  Press  of  May  1,  1915), 
I7"i.722  Ions  of  ore  was  treated  in  this  mill  in  1!»14,  so.  althougli  only 
a  test  mill,  it  handles  a  fairly  large  tonnage.  Dnring  tVie  month  of 
K°hrn:irv  I'Jir).  OO.iro  of  the  eopnor  occurring  in  the  form  of  sul- 
phides was  recovered.  The  mill  has  been  visited  hy  mining  men  from 
all  parts  of  the  world. 


l.iiTATIIlN    1\    A    .MKXIIXN     MILL 


91 


FLOTATION   IN   A   MEXICAN   MILL 


lly  A  Si'KciAL  Correspondent 

(From  tilt-  Mii'iii',1  mill  Siientifiv  I'n'ss  of  July 


:i.  i:n.3t 


l'Ki->t;NT  t'oxcKNTinriNn  M HI  KIDS.  Tlie  mill  ivceives  200  tons 
piT  day  of  crude  mine  ore.  After  lieiiii,'  erii.slied  lo  2-ineh  size,  tliis 
ore  is  passed  over  a  pieking-helt,  where  oiu'  ton  of  liigli-grade  ore  and 
four  tons  of  waste  ai'e  removed  eaeli  daj'.  Tlie  remaining  l!t5  tons  of 
seeond-eliuss  ore  is  crushed  in  stamp-batleries,  to  pass  a  -t-mesh  sereeiL 
Lime-water,  in  the  ])roport'on  of  7  of  water  to  1  of  ore,  is  added  in 
the  battery.  The  pulp  from  these  Is  elassitied  roughly,  the  coarse  sand 
being  ground  in  a  llardinge  mill  to  pass  a  20-niesh  screen.  Tiie  pulp 
is  again  elassitied  roughly  into  four  sizes  of  sand  and  one  size  of  slime. 
The  sand  is  concentrated  on  Wiltlry  tables  and  the  slime  (after  being 
settled  to  7 :  1  in  cone-bottom  tanks]  is  eontentrated  on  Deister  tables. 

The  slime-tailing,  from  the  Deister  tables,  is  re-eoneentrated  on 
vanners.  The  tailing  from  the  vannei-s  s«'ttles  to  'AS  tons  of  water  per 
ton  of  slime;  the  water  being  further  reduced  to  ij:!  in  a  vacuum- 
tilter.  The  filter-cake  is  washed  with  weak  barren  solution  before 
being  sent  to  the  cyanide  plant. 

The  saiuJ-tailing  from  the  WilHey  tables  of  the  stamp-n>i!l  is 
classified  carefuU.v  in  mechanical  classifiers;  the  slime  under-size  joins 
the  slime-tailing  from  the  re-concentrating  vanners,  and  the  sand 
(after  the  addition  of  cyanide  solution)  enters  the  tube-mill  circuit, 
where  it  is  .joined  by  50  tons  per  day  of  dump-tailing.  AH  tube- 
milling  is  done  in  cyanide  solution.  After  passing  through  the  tube- 
mills,  the  combined  current  and  dump  sands  are  re-concentrated  on 
Wilfley  tables.  The  tailing  from  these  tables  is  classified,  the  coarse 
saiul  re-entering  the  tube-mill  circuit  ami  the  slimed  sand  being  tbick- 
eiu'd  in  three  24-ft.  Dorr  vats  before  entering  the  cyanide  plant. 

MKT.M.I.1  RGK'AL    IlKSlLlS   OF    FKFJSKNT    MktiioDS 


Gold, 

Silver, 

Co|i|)ei-. 

Lead. 

oz. 

oz. 

'/« 

'; 

0.1 

:!5.4 

0.25 

0.7 

2.0 

r.Ton 

2.0 

10.0 

0.03 

is.o 

0.15 

0.4 

The  feed  lo  the  stain|i-iiiill  assiiys 

The  concentrate  ass.Tvs 

The  tailing,  after  concentration,  assays 

The  recovery  therefore  is:  gold, 
lead.  45'.; . 

Necessity  kor  Better  Concentration.     The  above  data  show  that 
a  little  more  than  half  'lie  gold  is  being  fecovered  in  concentration, 


t)5  :  silver,  48  ;  copper,  35  ;  and 


I: 


92 


rHK    FLOTATION    l'KOCF> 


iuul  tliiit  llir  rci-()\rrv  (in  sil\rr.  Irail.  iiii.l  ropjirr  is  loss  IIkiii  iiiilf  tho 
L-(iiit(-'iits  ill  tile  original  nvv. 

Tests  iiKJieati'  tiiat  mure  tiiaii  ltd',  of  the  niet-ij  in  tlie  oiiginal  ore 
(leeiirs  ill  tile  form  of  sillpliides.  Ileiiee  iialf  of  tile  nietallie  sul])iii(ies 
of  tile  orisrinai  ore  enters  tiie  eyuiiiiji'  i)laiit.  Tliis  is  um'  siraljje  for 
tile  following'  reasons: 

1.  Tile  extraction  of  silver  from  swliiliide  metals  is  ])o<ir  in  the 
eyaiiide  plant  :  tlie  etneeiitrate  iirodueed  from  jmnning  current  residue 
assays  between  30  and  100  oz.  silver  per  ton,  a'ld  the  tailiiejr  from  ])aii- 
niiig  iii\arialily  assays  below  2  oz,.  even  when  the  residue  assays  as 
high  as  5  oz. ;  showing  that  the  poor  e.\traetioii  is  due  to  iindis-solveii 
silver  in  the  sii!i)hides. 

2.  The  presence  of  metailii'  sulpliidis  increases  tlie  cyanide  eon- 
sumption.  The  ehemical  eonsuiiiption  of  cyanide  is  reduced  Irom  4  to 
1  lb.  per  ton  when  tiie  metallic  sulphides  are  removed  from  the  head- 
ing to  the  eytinide  plant.  The  present  exeessive  eyauidc  e()nsuiiii)tion 
is  line  aliuo.st  entirely  to  the  .solution  of  copper  from  the  ore. 

;i.  The  presence  of  copper  and  zinc  sulphides  in  the  eyanide  pulp 
fouls  the  solution,  thus  deereasing  the  extraction  from  the  rest  of 
the  ore. 

The  possibility  of  improving  results  by  better  eoneentratiou  of  the 
ore  has  long  lieeii  recognized.  For  this  reason,  arrangements  were 
made  for  re-eoiieeiit rating.  Both  arrangements  have  efi'eeted  a  re- 
duction of  a.ssay-value  in  the  final  residue  and  a  corresponding  in- 
ereiuse  of  profit. 

^IiOTiioDS  FOK  IiU'KovixG  Pkesent  CoNCFNTK.vTio.v.  Lately,  exten- 
sivi  tests  have  been  made  to  determine  the  po.s.sibility  of  still  elo.ser 
eoneentratiou.  Careful  panning  reduces  the  average  feed  to  the  cya- 
nide plant  from  18  oz.  silver  to  10  oz.  per  ton. 

Canvas  tables  give  slightly  poorer  results.  A  full-sized  canvas 
table,  treating  tailing  from  thi'  Deister  tables  (assaying  20  oz.  per 
ton  I  produced  1')  oz.  tailing — an  extraction  of  25%.  Further  tests 
along  this  line  were  diseoiitiiiue(l  on  account  of  securing  much  better 
results  from  laboratory  flotation  tests. 

LAHOKATt)KY  Fi.OTATio.v  Tksts.  All  flotation  tests,  made  in  the 
laboratory,  were  nin  in  separatory  funnels.  The  general  procedure  in 
the  tests  was  to  mix  100  grams  of  minus  200-mesh  ore  with  water  in 
l)roportion  of  four  of  water  to  one  of  ore.  Suitable  amounts  of  oil 
were  then  added  and  the  mixture  shaken  violently.  After  allowing 
the  pulp  to  settle  for  a  few  moments,  the  bottom  cock  of  the  funnel 
was  o]icned  and  the  tailing  run  into  a  second  separatory  funnel  for 


II.iiTATlDN    IN    A    MKXICW    MM. I. 


!i:i 


iinotlier  flotatioii  trcatiueiit  ;  thf  cock  liciii^'  >'liisc'l  licftirc  tlic  t'rotli 
began  to  run  out.  Tliis  jn-ocess  was  rcijcatcil,  on  the  tailing,  fniiu  live 
to  seven  times.  Several  hundred  tests  have  been  run,  all  possible 
variations  of  conditions  being  tried.  The  results  of  the  tests  led  to 
tlie  following  conclusions: 

1.  All  ores  from  tiic  mine  may  be  treated  by  flotation.  Semi- 
oxidized  ore  from  one  level  yields  a  tailing  a.ss<iying  ]()  oz.  silver  per 
ton,  while  the  oxidized  ore  from  another  level  gives  a  tailing  contain- 
ing oidy  2  oz.  per  ton.  The  tailing  from  average  ore.  when  conditions 
for  flotation  are  right,  is  4.5  oz.  silver  per  ton. 

2.  The  grade  of  tailing  api)ears  to  be  independent  of  wliether  the 
origiiuil  ore  is  treated  by  flotation,  or  whether  wet  concentration  pre- 
cedes flotation. 

;i  The  alkalinity  during  flotation  must  be  between  0.01  and  O.Oo 
lb.  per  ton  of  solution.  The  best  results  are  secured  when  the  alka- 
linity is  0.025  lb.  When  the  alkalinity  is  too  low,  the  extraction  is 
poor  although  the  concentrate  is  clean.  When  the  alkalinity  is  too 
high,  both  the  extraction  aJid  grade  of  concentrate  are  poor.  When 
the  alkalinity  is  right  (0.025  Ib.j  both  the  extraction  and  grade  of 
concentrate  are  best.  The  maintenance  of  proper  alkalinity  will  re- 
quire the  most  care  of  anything  in  the  plant :  although  it  will  not  be 
more  difficult  than  the  maintenance  of  jiroper  cyanide  strength  in  the 
cyanide  plant. 

■i.  The  dilution  may  range  between  :Ji:  1  and  7:1;  with  the  best 
results,  on  average  ore,  between  4:1  and  6:1.  When  the  pulp  is 
sandy  a  low  dilution  is  best :  pure  sand,  ground  to  200-mesli,  requires 
a  dilution  of  1:  1.  Average  slime,  like  the  Deister  feed,  on  the  other 
hand,  requires  a  dilution  of  8:  1.  Good  extraction  may  be  secured  on 
either  s<ind  or  slime,  provided  approximately  the  proper  dilutions  are 
secured  in  each  cast\  Proper  dilutions  will  be  easy  to  maintain  in  the 
plant,  for  the  range  for  the  best  work  is  comparatively  large;  and 
when  either  an  excess  of  siuid  or  an  excess  of  slime  occurs  in  the  ore, 
the  proper  dilution  will  automatically  adjust  itself;  for  the  sand  of 
itself  will  settle  to  a  thick  pulp,  while  the  slime  will  not  settle  well, 
but  will  remain  thin. 

5.  The  temperature  is  not  a  matt*'r  of  vital  interest.  The  ex- 
traction is  slightly  better  and  the  grade  of  concentrate  eon.siderably 
higher  when  the  temperature  is  over  lOO^F.,  but  good  results  have 
tieen  secured  with  the  tcmner.itnre  ns  low  ng  40°F.  Tt  will  v.o.f  ho 
necessary  to  arrange  for  heating  the  pulp,  especially  at  the  start. 

6.  Fine  grinding  is  necessary  for  good  results  in  flotation.    When 


■  H  THE    II.OTATION    I'ROCE^S 

t\\f  iriill-lii'ailiiijr  \\il^  mislii'd  In  tidiiH'tsli,  tin-  lailiii^'  t'l'diii  tintation 
assayed  (l.dt^  dz,  ^'dM,  iiiid  1 1  (iz.  silvci';  when  the  saiiu'  (iiv  was  cnislird 
Ik  lOO-iiH'sli,  till'  tailiiii;  assayed  0.04  nz.  fZdld  and  5  oz.  silver;  and 
when  tlie  eriisliinir  uas  i-arried  to  1200  inesii.  Ilie  tailin<?  assayed  0.02 
oz.  f^old  ami  :i.7.")  oz.  silver. 

|Tlu'  (luestion  III'  llie  kind  nf  eriisliin^  iiieehanisni  liest  adajtted  to 
preparing:  <>re  for  dotation  is  vital;  at  present  the  tnhe-niill.  hall-mill, 
and  dise-enisher  hold  the  lield.—  KhrroK.] 

7.  The  hest  flotation  asrents.  so  far  tested,  are  pine-oils.  Low- 
jiraih'  pine-oil  -rave  as  jjood  resnlts  as  the  hi<;her-jrrade  varieties. 
S.  S.  pine-oil.  of  the  (ieneral  Naval  Stores  Co.  (cost  26e.  per  jial.. 
f.o.ti.  factory  I  has  iriven  exceptionally  f^nod  resnlts.  h'or  tin  hest 
woi-k  in  flotation  it  is  neee.sstiry  to  have  this  o'\\  i)re.s».'nt  to  the  exten! 
of  O.t)  Ih.  i)er  ton  of  ore.  In  aetiial  plant-praetieo.  where  the  water 
is  returned  afjaiii  and  afjain  to  the  top  of  the  mill,  the  consnuiiition 
of  oil  will  j)rohalily  he  alioiit  [  Hi.  ])er  ton  of  ore.  This  oil  wdl  eost. 
delivered,  8c.  per  pound. 

I'iiie-lar  oil  is  much  cheaper.  It  i>;ives  j;ooil  extraction,  hut  the 
•rrade  of  concentrate  is  low.  Cresylic  acid,  when  used  with  ])ine-oils, 
increases  the  extraction  about  )  oz.  silver  per  ton.  This  hardly  pays 
for  its  use. 

8.  In  the  lahoralory  tests  the  <.'rade  of  concentrate  was  low. 
averas;in;_'  200  oz.  silver  ])cr  ton.  This  concentrate  cotdd  he  raised 
to  ]10()  oz.  h.v   re-t;-eatinj;  the  concentrate  by  flotation. 

it.  Cyanide  tests,  run  on  tailing  from  the  flotation  tests,  produced 
residues  ii.ssayiii<r  less  than  1  oz.  silver  per  ton,  with  a  cyanide 
consumption  of  less  than  1  Ih,  per  ton. 

10.  The  dump-tailing  cannot  be  easily  treated  by  flotation. 
When  the  methods  of  flotation  that  are  applicable  to  mine  ore  arc 
applied  to  the  [)um])-tailing,  the  results  are  nil.  Furthermore,  when 
the  water  tli::t  has  been  in  contact  with  the  pump-tailings  is  used 
for  diluting  mine-ore,  the  mine-ore  cainiot  be  tr,  ated  advantafjeously 
bv  flotation.  P^xperiments  show  that  both  these  effects  are  due  to  the 
|)resence  of  soluble  sulphates  (chiefly  those  of  magnesium  and 
calcium)  in  the  pump-tailinj;.  Tiie  in.jurious  et^'ect  of  iiiafjrnesiiim 
sulphate  can  be  overcome  larpely  by  an  excess  of  oil.  No  metiiod 
cd'  overcomiiifj  th(>  in.jui-ious  effects  of  calci\im  sulphate  lias  yet  bee:, 
liiscnvered  in  the  tests. 

TVlii!-  the  d!!!!iii  •;i!li!!f  IS  wnsUcd  ill  fj'OK!'  w:!*:'!'  \'.:<.\\'  ::  A  s/;:i 
times,  before  being  tivated  by  flotation,  the  results  of  flotation  an' 
as  satisfactory  as  is  the  i>ase  with  mine-ore.     However,  a  plant   for 


II.oTATKiN    IN    A    MKXICAN    Mil. I. 


Il;") 


wasliiiij;  tlic  liiiiiip-tiiiliiif;  woiilil  Ijc  inui-c  fXpcii.sivL'  than  tii''  small 
tonnage  of  this  material  warrants,  and  tlie  upcratiiin  of  such  a  plant 
Wdiihl  necessitate  tiie  waste  ol'  more  water  than  is  availahle.  Sonic 
itlici'  method  of  renderinfr  the  durn])-tailinfr  susecptihie  to  flotation 
may  he  d(  vised;  Imt  the  small  tonnaf^'e  does  not  warrant  any  extended 
investisjation.  Tiie  hest.  tiling'  to  do.  especially  at  the  start,  is  !o 
send  the  dnmp-tailini^  dire<'l  to  the  cyanide  plant  (after  enncen- 
tratintr  tiie  pri'oiind  sand  on  Wijfleys)  as  at  present. 

11.  As  a  result  of  the  lahoratory  cNperiiuent,  it  wa.s  deeiilcd 
that  fullsizcd  tests  should  he  conducted  in  the  plant  on  run-of- 
inine  ore. 

I'l.AN'i'  Thsts.  h'or  this  iiurpo.se.  there  were  set  aside  for  the 
flotatiou  circuit:  one  battery  of  five  stamps,  two  Wilfley  tables, 
one  elas.sitier,  one  tube-mill,  one  24ft.  settler,  and  one  pump  for 
returning  the  water  from  the  sottling-iaiik  to  the  head  of  the  mill. 

A  fiotation-eell  of  the  pneumatic  type  was  first  tried.  When 
treating  20-oz.  heading  this  inaehine  produced  a  290-oz.  concentrate 
and  a  15.3-oz.  tailing.     This  was  far  from  satisfactory. 

Another  machine  consisted  of  a  series  of  mechanical-agitation 
chambers,  alternating  with  a  series  of  settling-chambers.  From  the 
start,  this  machine  has  given  excellent  results.  In  spite  of  many 
mechanical  difficulties,  and  trouble  with  inexperienced  operators,  the 
tailing  from  the  plant  has  iveraged  but  little  above  5  oz.  silver 
per  ton.  and  the  concentrate  has  averaged  above  600  oz.,  without 
re-concentration. 

The  chief  weaknesses  of  mechanical  agitation,  as  ascertained  in 
this  mill,  are  as  follows: 

1.  The  complex  system  of  shafts  and  counter-shaft,  with  the 
coi'rc.sponding  drives,  bearings,  etc. 

2.  The  difficulty  of  adjustment;  any  slight  change  in  feed 
necessitating  a  change  in  the  valves  of  each  chamber. 

:!.  The  difficult.v  of  the  passages  Iietween  chambers  becoming 
clogged. 

Si'BMKRGKD  AciiT.vTiox.  It  has  been  attempted  to  evolve  a  flotation 
machine  to  overcome  these  weaknes.ses,  and  at  the  same  time  give 
results  as  good  as  the  mechanical  agitation  plant.  A  small  machine 
(capacity  15  tons  per  day)  has  been  constructed,  and  this,  after 
many  alterations,  has  yielded  a  3.7-oz.  tailing  and  a  680-oz.  concen- 


I 
I 

I- 


novel    principle    of    flotation — that    of    submerged    agitation — the 
mixture  of  pulp.  oil.  and  air  being  violently  agitated  in  a  partly 


96 


THE    KI/)TATION    I'ROCKSS 


rU>svi\   (•liaiiil..T,    under   tlie    liyiln.sti.lii-    jmi'susiiiv   of   s.-vcral    lr..t    o|' 
|>ill|)  ill  the  M'ttliiijf-clijiMiliiTs  above. 

In  roust luctioii.  this  iiiacliiiic  is  siniplrr  than  llie  iiiai-hin,'  usin^r 
meclianical  aKJIation.  It  ••(insists  essentially  of  a  V-shapeil  liox  or 
trougli,  divided  into  eoiii|)artnients  liy  a  series  of  vertical  partitions. 
At  the  hottoiii  of  i-aeh  jiartitioii  is  an  a^'itation-ehaiiiiier.  Airilation 
is  supi>lied  hy  a  paddle-wheel  in  each  ehainher.  All  the  paddle- 
wheels  are  mounted  u])oii  a  sin«l..  horizontal  sliaftiii>r.  which  passes 
the  iMitire  lent,'th  of  the  trou^'ll.  leaviiif,'  tin-  end  partitions  throu^rji 
sturtiiifj-ho.xes.  The  pm1|)  enters  each  asitation-ehainl.er  throiii;li  an 
opening'  arouiKl  the  shafting,  and  leaves  the  agitation-chaiiiher 
throuf;h  an  adjustable  ajtertiirc,  at  a  slif.'ht  distance  from  the  shafting 
The  atritator  thus  acts  sli<;litly  as  a  centrifuKid  pump,  overcoming'  the 
friction  loss  in  the  imssajre  from  one  coin|)artiiient  to  another,  ami 
keepins:  the  heif,'ht  of  the  pulp  the  .same  in  all  the  settlinfr-chambcrs. 
The  adjustment  of  the  aperture  is  arrans^'cd  to  increase  or  dcerea.se 
the  centrifugal  force.  This  adjustment  oeca.sions  much  less  diniiMilty 
than  is  experienced  in  mechanieal  a^jfitalion.  where  the  How  from 
one  eoiiipartmeiit  to  another  is  merely  throttled. 

Also,  ill  the  new  plant  there  are  no  pipes  to  become  clofrfred, 
the  pa-ssa^e  of  pulp  from  one  cell  to  another  being  along  a  rapidly 
revolving  shafting,  which  keeps  all  material  in  suspension.  The 
concentrate  overflows  from  both  edges  of  the  trough,  thus  being 
removed  more  promptly  than  in  a  plant  using  mechanical  agitation. 

Further  tests  with  the  small  machine  are  being  made,  and  a 
larger  machine  (cajiaeity  40  tons  per  day)  is  being  constructed,  for 
thoroughly  testing  the  princi|)les  involved.  The  40-ton  machine  will 
be  constructed  witli  the  idea  of  using  it  for  re-concentration  of  the 
concentrate,  should  a  full-sized  flotation  plant  be  installed. 

Si.Mi'LK  Mkcii.vnical  A(iiTATiON.  The  maeliine  ha.s  now  been 
operating  intermittently  for  a  month.  During  that  month  it  ran  si.x 
da.vs  continuously,  treating  2.")  tons  of  29-oz.  pulp  and  producing 
6.4-oz.  tailing  and  GOO-oz.  concentrate.  During  the  first  five  days 
of  the  following  month,  careful  tests  were  run  to  compare  flotation 
results  with  those  from  current  concentrating  practice.  The 
following  tables  give  the  summaiy  of  results  from  these  tests. 

^rii.i.-TK.-^T.-^.  Flotation  v.  I're.sent  (■'oncentration  Practice.  Flota- 
tion plant  takes  25  tons  per  day  of  mill  heading  after  being  crushed 

to    20-!!!es!!    bv    St.-iiiins     ! 

a  tube-mill. 


.  T,,,.,.<.^.   Oil    ^r  :iiit-_\.i,  aiiti   ;)asN;-i!    ;iiriiugii 


KlnlMhiN    IN    A    MKXICW    Mll.r 


Ml  I  \r  I  I  Kc.ic  \\.  lU  ^1 


I'm  Ton  ok  OnrdixAi.  Oiu.  I'^i 


Kioi 


Tong. 

Mill-heading    l.OOOO 

Wiltley  lonreiitrato   0,i»313 

Wlllloy   tailing    M.9tiS4 

F'lotation  concentrate rt.0207 

Flotation  tailing n.'.'i;" 

Cyanide  residue   

Cyanide  Inillion    


Licji  inATio.Ns* 

Wilfley  and  flotation  (oncentrale,  tons  0.52 

Gold,  0.12     oz.  at  $20 $2.42 

Silver,  35.10  oz.,  95^'f>  =  33.343  oz.  at  50c 16.t;7 

Copper,  37.-  -  0.3  =  2.7^', ;  2.S1  lb.  at  S.2c 0.23 

Lead,  ll.S^'c  -  1.5  z=  I0.3';'c ;  90%  at  3c 0.2S 


, J 

Vssay , 

, —  Conti 

•nts 

Gold. 

Silver. 

Gold. 

Silver. 

0.125 

39. SI 

0.125 

29. SI 

::.o7o 

fit;;!. 27 

0,09fi 

20.70 

O.ICiO 

19.70 

0.029 

19.05 

1.190 

»;92.7S 

0.1125 

14.34 

0.001 

1.9S 

0.001 

4.71 

0.001 

1.00 

0.001 

0.95 

0.003 

3.7i; 

Less  haulage,  freight,  and  treatment,  at  $19.t;7  per  ton $i.o2 

Less  taxes,  commissions,  etc,  7.44%. 1.4,-, 


119.01 


2.47 


Bankable  funds  from  concentrate  per  ton  of  ore $17.14 

Bullion  from  flotation-tailing,  per  ton  of  ore,  5.56  oz.  gross: 

Gold,  0.003  oz.  at  $20.67 $0.06 

Silver,  3.76  oz.  at  50c 1  ss 


Less  haulage,  treatment,  l.OSc.  per  oz. 
Less  express,  duties,  etc.,  7.8'', 


.$0.06 
.   0.15 


$1.94 


0.21 


Bankable  funds  from  bullion  per  ton  of  ore 

•Throughout  this  article  values  are  given  in  U.  S.  Currency. 
Products  Pkb  To.n-  ok  Okicinal  Ork 


Tons. 

Wilfley  concentrate..  .  .0.031:! 
Flotation  concentrate.. 0.0207 
Average  concentrate.  .0  0520 
Bullion    


Gold. 
Oz. 

3.07 
1.19 
2.327 
0.003 


Assay. 

Silver.  Copper. 

Oz.  %, 

663.27  2.75 

292.78  3.36 

675.00  3.00 

3.76 


Lead.     Zinc. 


12.00 
11.55 

11. SO 


12.7 
13.9 
13.2 


$1.73 


Insol- 

ulile. 

24.5 
34.3 

2S.4 


Phe-sent  Practice.  During  tlie  five  diivs  tlie  flotation  test  was 
being  run.  the  rest  of  the  mill  received  160  tons  per  day  of  the 
same  grade  of  niiii-heading.  This  was  treated  on  VVilfle.v  and  Dcister 
tables  and  the  tailing  re-concentrated  on  Wilflevs  and  vanners. 


|! 


08 


THE   FLOTATION    I'KOCKs^S 


MiiMiiiK.K  vr    Rh^iiis.    I'm  Tus   m    Ouk.inm    Okk 

TOIIH. 

Mlll-lu'a(Jiii^;    l.t.'iiOdii 

Stainp-niill  coiifcnirati'.  .  ii.0;il!.'iO 
V.illley  rc-concpiitiale.  .  (l.UO:!?:, 
Vaiint-r  ri'-conci'iitratf.  .  .  .O.oriocii 

Tailiiif?    ii.i.triM.", 

lU'Hidue   il.nr)Sl."i 

Dullion    

Bullion.  24. SS  oz.  ktobs:  koUI,  (1.0427  oz,;  silvfr.  l(',..-,0  oz.  |ifr  ton 

1,11(1   Hi  \  I  KIN,    I'KIl   Ton    Ol     OllK.INM,   UUK 

Concentratp,  tons (i.i>4i)>:." 

Gold,  0.0777  oz.  at  $20 $1..-,.-, 

Silver,  20.24  oz.;  95',c  at  .'iOc !i.t;! 

Copper,  2.41',^-0.:!  =  2.n';;   1.73  lb.  at  ,s.2c n.u 

Lead,  '.Kl'c-  \S>  =  ^.2''r:   90-;  at  :ic O.IS 


. Assay , 

—  C'ontt 

•llt.S     - 

Gold. 

Silver. 

Gold. 

Silver. 

0.125 

39.81 

0.1250 

39.81 

1  .",»:!o 

ulS.Oo 

O.OTOfi 

lS.94 

1.760 

2Nt;.44 

0.006H 

1  o,s 

0.7S0 

370.02 

OOOO.i 

0.22 

0.0,~)t| 

20.40 

0.0473 

i!t.r)7 

0.0II4S 

3,12 

O.OOlf. 

2.9.S 

0.0427 

Ui..-,9 

Less  hauluRe,  freight,  and  treatment,  at  $19. (17  per  ton $n.N(i 

Less  taxes,  conmiission,  and  ex|ietise,  7.44' ; O.m; 


$11. IS 


i.oi; 


Bankable  funds  per  ton  of  ore 

Bullion  from  current  tailiuK.  24. SS  oz.  gross: 

Gold,  0.0427  oz.  at  $20.(17 

Silver,  1(;..",9  oz.  at  r>Oc 


$9.S2 

^O.SS 
S.29 


l.ess  haulage  and  trealmenl,  at  l.Obe.  pei 
Lnss  express,  taxes,  etc.,  7.)i':'r 


Bankable  funds  per  ton  of  ore 

HitoiMtis  Pkr  Ton  ok  OuoaNAr.  Okk 


.  $o.2ii 
.    0.72 


$9.17 


0.9S 


5n.19 


Tons. 

Staniii-mill  concent  rate..  O.03(i50 
Wilfiey  re-concentrate. .  .0.00375 
Vanner  re-concentrate..  .O.OOOfiO 
Total    concentrates O.OlO.So 


Assay.  In.sol- 

GoUl.  Silver.  Copiier.  Lead.  Zinc.  ubl". 

Oz.            Oz.            'r             Tp  '^'r  'r 

1.93  olS.OO       2.3(;  10.40  12.9  24.50 

1.7(3  286.44       1.03  3.37  (i.O  4.^.2S 

0.78  370.92       1.00  5.86  4.7  .•;t;.22 

1.90  496.00       2.41  9.7  12.1'.  27.00 


Costs.     Labor  and  rejtair  cost.s  will  remain  about   the  .same   a.s 

now.      Two   high-class  ojjerators   in   the   present  re-treatnieut    I'.lant 

..'111                        »                iiji                       1                                           .                  -           .t  /-•..•               ^_» 

'.*.;:;    :;f   ri."];i;i:"';;   ;;\'    ;  lirir  t'liCJip   fipcrilturs  ill   TuC  norriTlOit   jUciiiT. 

Power  consumption    will   be    increased   about  40  hp.      This   will 
cost  5c.  per  ton. 


KIiiTMliiN    IN     \    MKXICW    Mill.  99 

( >il  .(iiiMiiiiiitioii  Will  111  jiImhiI  t  II).  |pt  I  1(111  III  (ire.    ill).@8c.  =  2c. 

•If     toll. 

Tiif  tiiiiil  iiicrca.M'  in  the  fnsst  «(  eoiiccutiatidii  will  tlierct'ore  be 
nlxiiit  "c.  per  tdii. 

Till'  picsiiit  lyaiiidc  (•(insuinptiim  pep  ton  (if  on-  is  6  11).,  of  which 
2  II).  is  int'ihaiiicaJIv  lo.>*t.  Small  lahoratory  tcst.s  show  that  the 
chciuiiiil  (■()nsuin|)lioii  of  lyaiiidc  when  Hotatioii-tailiiif;  is  tivated, 
i.s  only  1  111,  jxr  ton  of  oir.  This  is  .'(  II).  less  than  the  consunip- 
tioii  when  1  HIT.  lit  tailiiiff  is  treated,  [f  tiiis  result  is  .sustained  in 
actual  plaiit-|)iactice.  the  saving  in  cyanide  alone  will  amount  to 
■i  X  I!'"-  — "  '>7c.  i)er  ton  of  ore. 

The  present  cost  of  i)recipitation  and  meltiiifr  is  2.56c.  per  tine 
ounce. 

In  present  practi(>e  Ki.ti  fine  ounces  are  i>roduced  per  ton  of  or<.'. 
When  flotation  tailing  is  treated,  only  .'J. 7  oz.  are  produced  per  ton 
of  ore.  This  means  an  I'.xcess  of  12.0  oz.  produci d  in  present  practice: 
120  X  2.060,  =  ;{;{('.   i)er  ton   of  ore. 

Fin  AM  ur,  Sr.iiKMKXT 

Flotation  v.  I'le.sent  Practice,  Per  Ton  of  Original  Ore. 

Present 
practice.  Flotation. 

Bankable  funds;  niarlu'tinR  (onceiitrate $9.82  $17.14 

Baniiable  funds;   niarlcetinK  bullion S.19  1,73 

Increased  cost  of  concentration 0.07 

Decreased  cost  of  c.vanide 0.57 

Decreased  cost  of  nieltiUB  and  inecipilation 0.2S 

$1S.08  $19.72 

Increased  luoflt  i)er  ton  from  flotation,  200  tons  |ier  day  ;it  $l.t;4  =  $:l2S 
increased  inoftt  per  da.v  or  $9840  increased  profit  per  month. 

The  above  is  calculated  on  the  ha.sis  of  results  from  a  single  mill- 
test  of  5  days'  duration.  During  this  interval  the  heading  to  the 
mill  and  tiie  residues  were  e.xcessively  high;  indicating  a  greater 
advantage  in  favor  of  the  flotation  plant  than  is  actually  warranted. 

The  estimate  of  probable  profit  may  be  revised  roughly  by  using 
the  metallurgical  results  of  the  pa-st  two  months  for  the  basis  of 
calculation.;.  During  two  months  the  heading  to  the  cyanide  plant 
has  averaj.'ed  17.8  oz.  silver,  and  the  residue  has  averaged  2.75  oz. 
per   ton.      The    residue    from   cyanide-flotation    tailing   would   as.say 

1    ;;.:.    ]/ir    ;;>;;.       ii;is    iruiicaiio    an    iUOi  ea.-M.-ii    t.\iraclloii    oi'    1.75    oz. 

silver  per  ton  of  ore.    1.75  oz.  at  41c.  —  72c.  increa.sed  proiit  per  ton. 
The  indicated   decrea.se   in   cyanide  consumption    (as  determined 


100 


TriE  rr.oTATioy  prockss 


solely  ill  tlio  laiionitory  i    is  :>  Ih.  per  ton  ol"  ore.     Kcducinsjr  tliis  to 
21  X  I!l<'.  =^47c'.  per  ton  of  oro. 

The  (l('crcii.sc(l  cost  of  pivcipitatioii  and  nirltinf;  may  he  tifrurod 
as  follows::  Cost  of  nrccipitation  and  nitdtinfj,  por  tine  ounce,  has 
l)C(>n  2Af.  The  decivasod  production  of  bullion.  dui>  to  flotation, 
would  he  11  oz.  per  ton  of  ore.  11  oz.  at  2.4e.  =  26.4e.  When  fixed 
charges  are  considered,  this  .should  he  redrced  to  20e.  per  ton. 

When  tlic  ])rofit  fro;ii  marketing  an  increased  amount  of  lead 
and  copper  Is  halanced  afjainst  the  increased  loss  occasioned  Iiy 
marketing  the  silver  and  gold  as  concentrate  instead  of  hullioii, 
thei'e  is  a  deficit  of  17c.  per  ton  of  ore. 

Tiie  matter  may  hi'  summarizi'd  as  follows: 

Per  ton. 

Increased  extraction  $0.72 

Decreased  cyanid"  -Dtisiimpiion   (1.17 

necrei.Kod  cost  oi  procipitatinn  and  melting 0.20 

$1.39 
Increased  cost  of  niarl^etins; 0.17 

Protits  per  ton  of  ore  $1.22 

The  average  tonnage  of  min"-ore  for  the  past  two  montiis  has 
heen  r>7()l  tons.  Hence  the  indicated  increa.se  in  monthly  profit 
would   he  5761  X  $1-^2==. t7()28  42. 

I.vsT.viJ,.vn(».\  UP  Flotation  rr,.\NT.  Sliould  a  flotation  ])lant  be 
installed,  operations  in  tlie  stami)-inill  will  continue  as  at  present; 
tiiough  it  may  be  deemed  advisable,  after  the  flotation  plant  is 
ruiuiiiig  smoothly,  to  eliminate  concentration  in  the  stamp-mill,  and 
dej)end  upon  the  flotation  jihint  for  all  coiu'cntration. 

Ke-concentration  of  current  tailing  on  vanners  and  Wilflcys  will 
be  discontinued  from  the  start. 

The  dump-tailing  will  be  treated  as  at  present,  with  the  exception 
that  this  material  will  enter  the  plant  only  in  the  day-time.  One 
tube-mill,  one  classifier,  one  elevator,  and  the  re-concent  rating  AVilfley 
tables  will  be  kept  sepai'ate  from  this  circuit,  which  will  be  in 
cyanide  soluti(ui.  All  lime  for  the  cyanide  i)lant  will  enter  this 
circuit.  One  of  t!ie  24-fl.  tanks  and  one  of  the  pumps  must  bi' 
res^'rved  for-the  dump-tailing  circuit. 

All  the  tutie-milling  ot'  current  sand  tailing  will  be  ihuic  in 
niill-wMtcr    Instea.il  of  cvanide  solution. 

The  ground  sand,  together  with  tlic  cuiTcnt  slime,  will  be  settled 
ill  two  of  the  2!  ft.  thii'kening-tanks.  and  will  then  enter  the  flotalion 


FI.UTA  rloN    IN    A    Mi;.\l('\N    .MII.I. 


101 


l)laiit.     From   the   flotation   phuit,   the  tailing   will   tlow   to   the   tv " 
;j:J-tt.   thiekeuiijg-taiiks.     The  thiekeiied   piilit   iVom  these   tanks  \vi' 
be  de-watered  and  wa.shed  in   the  vacuuiii-Hltcr  before  entering  the 
eyaniili'  i>lant. 

All  lime  I'or  the  niill-eireuit  will  be  added  as  an  emulsion  t'>  the 
flotation-tailing  launder,  where  it  will  be  under  direct  eontrol  of 
the  tlotatioii-()j)erator.  The  water  in  the  2.'i-ft.  thiokening-tanks  will 
contain  about  0.4  lb.  dissf)lved  lime  per  ton.  This  is  ample  for  go(Kl 
.settling  The  overflow  from  the.se  tanks  will  be  reduced,  by 
consumption,  to  about  0.1  lb.  per  ton.  This  is  sufficient  for  fair 
settling  in  the  cone-bottom  tanks  of  the  stamp-mill.  By  the  time  the 
pulp  reaches  the  24-ft.  thickening-tanks  the  lime  will  lie  reduced 
to  O.Oli  11).  per  ton.  This  low  lime  will  be  e.\tremely  detrimental  to 
good  settling  in  these  tanks. 

IxsT.\Li,.\Tiox  Kkc^iikkd.  The  matter  of  supplying  proper  settling 
and  de-watering  facilities  will  be  the  most  serious  and  most  expensive 
]iart  of  the  installation. 

The  two  24-ft.  thickening-tanks,  to  be  us<'d  in  the  flotation-circuit, 
must  be  triple-decked.  It  will  also  probably  be  found  neces-sar.v  to 
double-deck  the  :i2-ft.  steel  thickening-tank.  The  work  on  settling- 
tanks  will  cost  a'oout  $6000. 

Hy  inerea.sing  the  settling  capacity,  the  pulp  will  proliably  be 
settled  to  a  sufficient  thickness  s<i  that  the  vacuum-filter  will  be  able  to 
handle  the  combined  sand-slime  feed. 

It  nuiy  be  f(mnd  necessary,  however,  to  add  another  unit  to  this 
plant.     This  will  cost  $2000. 

The  flotation  plant  will  consist  of  two  units  (each  of  which  will 
be  able  to  treat  the  total  tonnage  of  current  tailing'  and  one  smaller 
clean-up  machine.  The  whole  plant  will  cost  about  $.5000.  A  filter- 
press  for  handling  the  concentrate  will  cost  .$2000.  Tanks,  air-lifts, 
launders,  and  buildings  will  cost  $2000.  Thus  the  whole  in.sfallation 
will  cost  $15,000,  or  .$20,000  at  the  most.  The  addition  of  the 
flotation  plant,  for  treating  current  tailing,  will  increase  the  profit 
about  $7000  per  month.  Practically  all  iin-  from  the  mine  may  be 
treated  bv  flotation. 


102 


TJIE    FLOTATION    i'lioCESS 


FROTH    AND    FLOTATION 

(From   Iho   Muiuiii  ami  Sriinlitir   I'i;-ss   of  .Inly   :;i.   I'.'lo) 

111  tlic  i>,sii<'  \\n-  XiiVfiiilicr  IDli:!  df  the  Cftlifnniia  .Inin-iinl  nf 
T<  iliit'ili,!/;/  tlicri'  api)i':irnl  ;in  artirlc  (|cs<Til)in^  llic  cxpcriiiieiitiil 
wiirk  (lone  oil  oil-ridtatiou  \>y  tlircr  sciiidr  studciits  in  tliu  I'liivcrsity 
of  CaliforiiiM.  Tlic  arlii'lr  is  ciititlcil  ■  Kxpfriiiu'iils  on  the  Klmnru 
Prociss  of  Oil  Coiiri'iitralion'  ],y  \V.  I-',  ('oprlaiid.  Drurv  liutltT.  and 
.las.  11.  AVis.'. 

At  the  outset  tlicx-  .state: 

■"The  i)rores,s  depends  upon  the  fad  that  iiiinerais  with  a  metallic 
lustre,  when  treated  in  the  form  of  a  wetted  pulp,  adhere  to  oil.  while 
earthy  minerals  do  not.  Two  distinet  operations  are  involved;  first, 
the  sejiaration  of  tie'  inetallie  mineral  from  the  sraiisrue  oy  means  of 
oil:  seeond,  the  exfraetion  of  the  mineral  froiii  the  oil. 

'■'Ihe  ideas  iinderlyinf?  the  first  operation  were  ])a1ented  hy  -lohn 
Timihridgc  of  Newark.  N.  J.,  in  ]S78.  In  1886  Carrie  J.  Evrrson, 
of  Chiea^o,  eontrihnted  the  idea  that  the  eoucentrafion  was  aided  by 
the  presenee  of  an  aeid  solution,  and  i)atented  the  same.  Hut  the 
ah.sence  of  a  sui'c<'sst"ul  method  of  separating  the  mineral  from  the 
oil  prevented  the  ])raetieal  appiii'ation  of  these  early  patents.  Hurii- 
iiifr  the  oil  was  tried.  Imt  this  left  a  difficult  residue  to  treiit,  ami  the 
large  eonsumption  of  oil  madi-  the  method  too  expensive.  Settling 
the  mineral  out  hy  thinning  the  oil  with  ga.soline,  ether.  <'arhon- 
hisulphide.  cti-..  also  proved  too  i'\iiensive.  and  it  was  not  until  July 
1900  that  this  diffieulty  was  overcome,  when  ^Ir.  Francis  E.  Elmore, 
of  T,ecds.  longlaiid.  accoiii|)lished  the  separation  by  means  of  a  cen- 
trifugal machine,  similar  in  most  respects  to  those  used  in  sugar 
factories  and  in  milk  and  cream  separation.  This  contribution  hy 
]\lr.  Eliiioi-e.  then,  made  the  process  feasibl'\" 

I  They  give  an  illustration  of  the  plant  design(>il  by  the  Oil  Coii- 
centration  Syiidicat(>  and  'deseribe  the  operations.  Their  own  ;\\i- 
I)aratus  is  shown  in  photographs  and  they  give  details  of  tiie  tests 
made  on  various  ores.     In  brief,  they  obtained  the  followint:  results. 

Rxtrac- 
Character  of  ore.  tion,  % 

(JoIU-qiiartz    ore    Sf; 

Silver  ore   -r, 

ropiier-sohist  taillni;   Sn 

Molybdenite  ore    7-, 


FROTH    AND    FLOTATION' 


103 


'I'Ikv  dfsoiilx'  tlif  nature  of  their  experiments  and  comment  on  tiie 
filets  disclosed  in  a  inosi  intelli^'ent  way.  We  (juote  the  salient  para- 
graphs.] 

"In  makin<^  a  test,  the  ore  is  first  crushed  to  the  desired  fineness, 
and  the  proper  eharcre  is  thoronsrhly  wetted  in  the  solution  to  l)e  used 
(usually  water),  thus  f(U'iiiin^'  a  thin  pulp.  The  oil  is  next  added 
and  till'  whole  ehartre  thoroufrlily  mixed  This  mixingr,  oi-  ai;itatioii, 
<'an  )»■  dune  in  two  different  ways:  The  charge  may  be  agitated  very 
grnily.  tlie  oil  licintr  kept  in  a  single  lake,  and  broken  up  as  little  as 
po.s.siblc  consistent  with  a  thorough  contact  of  pulp  and  oil;  or  the 
charge  may  be  agitated  so  violently  as  to  dash  the  oil  up  into  a  foam 
or  froth,  full  of  air  bubbles:  thus  a  very  thorough  contact  of  oil  and 
pulp  is  obtained.       •••#•• 

"Thi'ee  methods  of  mixing  may  be  used. 

1.  By  inverting  the  tube  several  times,  thus  allowing  the  ore  to 
fall  through  the  oil. 

2  Hy  i-otating  the  tube  in  a  horizontal  position,  thus  throwing 
till'  pul]!  up  on  to  the  surface  of  the  lake  of  oil. 

:i.  liy  violently  shaking  the  tube.  '  lius  producing  the  foam  effect* 
or  at  least  shattering  the  oil  into  small  globules." 

•     ••••• 

"The  solution  tised  in  the  concentration  is  a  matter  of  some  im- 
poi'tance.  Water  is.  of  course,  used  whenever  jwssible,  but  certain 
other  solutions  have  important  advantages.  As  before  stated,  an 
acid  solution  is  found  advantageous.  Tt  cleans  the  metallic  surfaces 
by  dissolving  the  metallic  oxide  coatings  that  may  have  formed  on 
tht'in.  Tt  inrrea.ses  the  specific  gravity  of  the  solution,  and  it  aids  in 
produi-ing  ihe  foam  effect,  which  is  due  to  the  generation  of  certain 
•rases. 

As  befori>  stated,  the  specific  gravity  of  the  average  oil  used  is 
about  O.f)  and  water  1.0,t  leaving  a  difference  of  about  0.1  for  buoy- 
ancy or  carrying  capacity  of  the  oil. 

The  idea  at  onc<'  suggests  itself  that  if  a  denser  solution  be  used, 
the  cni lying  power  of  the  oil  will  be  increased  correspondingly.  A 
.salt  (NaCl  i  solution,  for  instance,  gives  excellent  results.  A  saturated 
solution  of  NaCl  at  20T..  containing  about  2"';',  NaCl,  has  a  specific 
gravity  of  1.204.  This  gives  a  difference  of  0..S  between  the  specific 
gravities  of  the  oil  and  of  the  solution,  and  a  carrying  capacity  of 

the    oil    tnrer-Toiu    glertter    iiinn     Wiiii     nfiier    ,ui)iie.       "NoL    oiliv    (iocs    it 


I 


•[The  italics  in  all  these  quotations  are  ours.- — EnixoR.l 
i[In  the  original  It  is  .1. — Rihtor.I 


104 


THE    HX)TATIOX    I'KOCE>S 


f-'iv..  tr,,,,,,.,-  Inui.vaiiry  t,,  ih,.  ,,i|.  l,ut  ,7  <,/.„  „„/.,.  „u,i,ruiUu  in  pm- 
<hinmj  ih,  fiHim  ,ir,rf,  and  pmhaMy  aids  in  liri^dit.-tiin^'  tii,'  nu-tallio 
surt'aiTS. " 

As  a  (MUii'lu.siori   tn  tli-  almvp  t'xiicrinicnls.  tiip   fdlhiwinL'  sutr-rcs- 
tinns  and  iiiferciiccs  ai'e  ai)peiid('d  : 

1.  As  Ki:r.AKDs  Tin:  Wetted  I'rE!..  As  fai'  as  could  ho  .iH.Tniincd. 
l);irti(dcs  witli  citlici'  nictallic  or  ii(in-metallic  snrfares.  \\hn\  in  a  dry 
state,  alike  adhere  to  the  oil.  Furthermore,  there  is  no  ntKiuitv  of  oil 
I'or  -.vater.  as  shown  l.y  the  faet  that,  an  oiled  surfaee  eamiot  b<>  wetted. 
Hence  if  a  metallic  particle  he  thorouphly  wetred,  a  water  surface 
and  not  a  metallic  surfac-  is  exposed  to  the  oil;  and  the  former,  as 
hefore  stated,  has  no  affinity  for  the  oil.  It  is  evident  then  that  the 
water  film  must  first  be  displaeed  hefore  the  oil  and  mineral  can 
come  in  eontaet  with  eaeh  other.  This  displacement  is  hardly  i)rob 
able  if  the  water  film  is  in  intimate  eontaet  witlr  the  particle,  and  it 
seems  mor(>  probable  that  the  difTerentiation  is  due  to  the  fact  that 
non-metallic  surfaces  are.  and  metallic  surfaces  are  not.  actually 
witted.  If  this  be  the  ca.s<\  a  careful  study  of  the  relative  wetting; 
of  difVercnt  surfaces  would  be  an  important  line  of  investigation. 

2.  The  ratio  of  the  exposed  surfaee  to  the  wei^'lit  of  the  particle 
should  be  as  larfro  as  possible.  I)eeausp  tlie  total  adhesive  force  is 
increased  with  an  inercase  of  the  surfaee  expo.sed  to  contact  with  the 
oil.  This  eouditiou  is  best  realized  when  the  mineral  breaks  up  int(. 
thin  flakes.  It  is  evident  from  this  that  a  knowled','e  of  the  fissile 
eharaeter  of  the  minerals  in  f|uestion  is  important. 

;i.  One  fundamental  difficulty  involved  in  this  jiroce.ss  is  that  it 
undertakes  to  concentrate  and  float  .v  heavy  metallic  mineral,  and 
s^ink  the  liyrhter  trangue  minerals,  but  this  jioint  is  Tiot  necessarily 
t^ital  to  the  process.  It  is  evident,  however,  that  the  heavier  the 
paiifTue  and  the  lifjrhter  and  mori'  fi.s,sile  the  metallic  minerals,  tlie 
better  the  ore  is  adapted  to  this  method  of  concentr.ation.  This  is  a 
direct  reversal  of  the  id.'al  conditions  for  .iifr  or  vaiuier  concentration. 

4.  Anoiiii-r  <-haraeteristic  of  the  process  is  the  faet  that  the  ratio 
of  concentration  is  usually  small,  due  to  the  larsre  amount  of  <^an^^le 
occluded  by  the  oil  an.i  .-arricd  into  the  ronccntratcs.  This  ditlieulty 
is  increa.s<Mi  by  slimiiifr  the  gaufrue  minerals.  Sliming  of  the  nictallio 
minerals  is  no  disiulvantafre. 

F().\M  Efeect.— 77/r  fnain  iffict  i\  pruducnl  hi/  a  ry.l.  >,(  nnUn- 
tinn,  (si„ri(illif  in  arlil  ,,r  salt  snliilimis.  This  thmirs  Ihr  nil  into  a 
fruth.  irhiih  is  hmvilit  ,h,ir,i,,J  irilh  nir  nr  <,fhn-  gasis.     Thit  r/as,  of 


KUdTII      \ND    rl.dTVTIlIN 


lo:. 


(intrsi .  f/ivts  (I  ;jn  ntlji  in,  n  asi  <l  lni,>n<int  fnn-, .  Tin  ,,U  in  lliis  ,,,n(li- 
lion  atsuinis  a  vtrtain  load  of  mimral  and  hohh  it  in  a  ra-y  stable 
roiiditior..  The  (Jitinic  do,  s  not  stttlr  and  ,n;  rlo,id  on  standiiuj  as 
ill  ill.'  ra.s,'  of  the  Ifikf  t'rtVct.  Tlie  foam  I'ftVct  is  ln'st  adaiited  for 
litrlit  riaky  iiiiiictals.  siidi  as  molybdenite. 

The  work  aliov  oiitliiifd  susijircsts  niatiy  lines  of  further  investi- 
iration,  and  as  lliese  e(,me  to  lie  worked  out,  the  proeess  will  hrcome 
iiiorc  valuabie  and  nf  more  treneral  apnlication,"" 

lit   is  clear  thai    they  had  a  good      '-i  of  tiie  usefulness  of  the 
froth,  and  how  to  make  it.     I.,  the  employment  of  salt  and  aeid,  tliey 
antiei|)ated  (i.  1).  D.dprat.  for  liis  Hritisli  patent  for  the  use  of  salt 
and  sulphuric  acid  was  taken  out  on  Deccmher  11,  1D();J,  that  is,  two 
months  after  this  article  was  published.     The  early  work  of  L'.  V. 
Potter  (patented  on  Jainiary  11,  1002  i  and  G.  D.  Delprat  (beginning 
with  a  patent  dated  November  28,  1902)   did  not  involve  the  u.se  of 
oil.  liut  the  generation  of  gas  in  the  pulp  to  form  bubbles.     Aleide 
Froment   Hinder  patent  dated  June  4,  11)02)   connected  the  oil  and 
bul)l)le  idca.s.  and  it  is  his  patent  that  forms  tlii'  basis  of  the  .Minerals 
Separation  process,  to  which  in  ]!)0.')   (and  particularly  November  6. 
Tt06;   were  added  several  patents  obtained  by  U.  L.  Sulman,  II.  F. 
K.   Pieard.  and  .folin   Ballot,   for  the  agitation-froth  proecs,s.      Thus 
the.se  three  students  at  the  I'liiversity  of  California  had  touehed  upon 
an  idea  destined  to  be  of  tlie  greatest  importance  in  metallurgy,  but 
th.'y  did  not  know  it.     In  tlic  very  same  i.s.sue  of  their  Journal  of 
Tichnohgy  there  appears  an  arti(de  on  'The  Method  of  Obtaining 
Letters  Patent.'    The  irony  of  the  .iuxtaposition  is  evident  now.     We 
note  tliat   the  manager  of  this  sti  dent  publication   was  Arthur  II. 
Ilalloran,  then  a  junior  in  the  Tniversity.     He  became  a  member  of 
the  staff  of  the  Mining  and  Sci,  ntific  P/t.m  after  graduation  and  for 
some  time  after  his  father,  J.   F.   Ilalloran,  .sold  the  control  of  the 
paper  to  the  present  writer.     However,  it  may  not  be  .so  surprising 
that  these  young  fellows  failed  to  appreciate  the  importance  of  the 
suggestions  obtained  in  the  course  of  their  experimental  work,  but  it 
is  truly  remarkable  that  a  keen  investigator  like  their  profes-sor,  the 
late  Samuel  B,  Christy,  .should  have  overlooked  it,  at  a  time,  too,  when 
he  himself  was  at  work  on   kindred  research,   more  particularly  in 
cyanidation.     It  may  have  been  liis  alisorption  in  the  one  part  of  the 
suli.ject  that  prevented  him  from  ol))aining  the  right  focus  on  these— 

now.    to    us — de(>nlv    SUS^L'eslivi'    ('vncriinnnte Pimt.^d  1 


f 


106 


THE   FLOTATION    PROCESS 


m 


FLOTATION  AT  WASHOE  REDUCTION  WORKS,  ANACONDA 

By  E.  P.  AIatuewson* 

iFrom  the  Miniiiy  and  Scientific  Press  of  August  28,  191&J 

Till'  iiiiiicriil  that  is  two  milliiuftres  and  undfi*  in  size  is  sent 
to  the  llanliiijje  mills  for  re-grinding.  These  mills  are  10  ft.  diam. 
hy  4  ft.  long,  and  are  in  closed  circuit  with  simplex  Dorr  classifiers, 
one  cla.ssitier  to  each  mill,  6  mills  to  the  section,  and  8  sections  in 
the  establishment. 

The  overtiow  from  tiie  classifiers  goes  to  the  flotation  division, 
and  the  classitier-siind  is  returned  to  the  Ilardinge  mills.  At  present 
pebbles  are  being  used  in  tiie  Hardinge  mills,  but,  in  all  probability, 
steel  balls  will  ultimately  be  used.  \Vith  pebbles  the  Forbes  lining 
is  used,  but  with  steel  balls  in  use,  each  mill  will  be  fitted  with  a 
false  wooden  lining  to  ri'duce  the  diameter  of  the  cylinder,  and 
a  manganese-steel  lining  will  be  placed  inside  of  this. 

Ea<-ii  mill  ha.s  a  direct-connected  22r)-hp.  motor.  The  mill  titted 
with  pebbles  required  from  95  to  115  hp.,  but  the  motors  are  madi' 
extra  luavy,  in  anticipation  of  the  use  of  steel  balls. 

In  each  section  of  the  flotation  plant  there  are  four  iMiiicral.s 
Separation  machines,  each  having  M  agitators  and  14  floating- 
compartments.  Below  these  are  six  Callow  cells  for  cleaning  the 
concentrate.  The  agitatoi-s  tor  the  AFinerals  Separation  machines 
are  made  of  gun-metal  and  are  driven  by  bevel-gears  from  the  main 
shaft.  (See  Fig.  17.)  Each  machine  is  driven  independently  by  a 
loO-lip.  motor,  running  at  :iH')  r.p.iii.  on  full  loml.  The  speed  of 
the  agitators  is  reduced  to  about  225  r.p.m. 

The  produet  from  the  machines  is  a  tailing,  which  goes  to  waste 
(from  this  tailing,  fire-bnek,  building-brick,  and  acid-proof  brick 
will  be  made  in  a  new^  brick-plant  now  under  construction)  ;  a 
concentrate,  which  is  sent  to  the  Dorr  thickener-tanks,  for  settle- 
ment— tliis  comes  from  the  first  three  cells  of  the  frothing-machines. 
The  rough  concentrate  from  the  next  six  cells  of  the  M.  S.  machines, 
is  further  cleaned  in  the  Callow  cells  (See  Fig.  18).  making  a  clean 
<-oncrntrate;  anil  the  middling,  which,  with  the  middlings  from 
the  remaining  five  cells  of  the  J[.  S.  machines,  is  returned  to  the  feed 
of  thes<'  same  machines. 

About  C  to  S  ii).  or  .mT  i>.  .•Miiiiiunic  acni,  per  ton  of  iiotation- 

♦Manager  for  the  Anaconda  Copper  Mining  Company. 


KLdTATIlIN    AT   TIIK    W  AMluK    KKDICTION    \V(>UK~.     \N\((lM.\  107 


ll),S 


Till",  ii.utation  rii(Mi:ss 


t'ri'il,     l>,    use  I,    loi,'i'tl|iT    willl     I  Wll     li)    tliri'i'    poUlnls    of    kiTllslMll'  sludj.'!' 

in'id  aiul  t'roiii  DMc-liiiir  to  one  ixmiid  (■!'  wood-croosote.  A  |)ortioii 
oi'  the  wood-crcosotc  is  added  to  tlir  head  of  tlie  IIar<liiij;e  mills, 
and  the  reiiiaiiidiT  is  added  at  the  head  of  the  .M.  S.  niai-iiines. 
'I'll,  pulp  is  heated  to  (id  or  70"  h\  ],y  steam  iiitrodiieed  into  the 
tirst  aizitatiiiir-hox.  The  method  of  addiii<r  the  reaj^eiits  is  iiniciin'. 
The  mixer  eonsisis  of  a  revolviiiir  disc,  to  the  eireiimfereiiei'  of 
which  are  attaehed  a  nniiiher  of  eiips.  The  ilise  is  set  vertically, 
so  that  its  lower  edj^e  dips  into  the  ])aii  of  acid,  or  oil;  as  the  disc 
revolves  the  cups  are  tilled,  and  later  diseliar^e  their  contents  into 
a  suitahle  launder  leadini;  to  the  tlotation  niaehiiies.  The  disc  is 
driven  hy   the   friction  of  a  wheel   ajraiiist   another  disc  attached  to 

the    main    drive.      'i'iie    w  1 1    is    run    at    constant    speed    and    any 

\ariation  in  i'eed  can  he  iiKuie  hy  eliaiifiiiig  the  point  of  contact 
lietweeii  the  wheel  and  the  disc.  In  addition  to  the  speed  rctfiilation, 
tile  amount  of  acid,  or  oil,  fed  lua.v  l)e  varied  hy  changing  the 
niimher  of  cups,  or  the  size  of  the  eiips. 

On  account  of  lack  of  s|)aee  in  the  old  mill,  now  heiiif;  re-modeled 
for  flotation,  an  auxiliary  i)knt  has  to  lie  installed  to  handle  the 
extra  slime  from  the  mill.  This  is  now  under  constnietion  and  will 
consist  of  20  l\.  S.  machines  of  the  same  type  jus  those  now  in  use. 
Fourteen  of  these  will  he  reiiiiired  for  treatinfif  the  current  slime 
from  the  miil;  the  i-emainiiit;  six  will  treat  old  slime  from  the  dump. 
This  will  lie  liroiiL.'ht  fr  ill  the  dump  dry  and  mixed  with  water 
hefore  trealiiieiil  in  the  maehines.  The  capacit.v  for  tlie  dnmp-sliine 
is  ahoiit  loot)  tons  i)er  da.v.  No  Callow  cleaners  are  to  he  used  in 
this  i)lant. 

The  concentrate  from  the  dotation  machines  is  thiekened  to  about 
etT^;  solid  in  Dorr  tanks.  TiO  liy  12  ft.,  the  spigot-produet  of  which 
goes  to  IH-ft.  <liam.  hy  12-ft.  face,  Oliver  filters,  each  having  a 
capacity  of  about  150  tons  daily.  -  r 

The  cake  from  the  Intel's  contains  about  18^,'  moisture  and  Mill 
be  fed  onto  a  conveyor  carrying  inill-fliie  concentrate  to  the  new 
roast iiig-plant  now  in  process  of  construction.  In  this  way  the  filter- 
cake  will  be  fairly  widl  mixed  with  the  concentrate,  so  that  a  generally 
uniform  feed  v.ill  be  obtained  for  the  roasters. 

At  the  jircsent  writing  two  sections  (out  of  eighth  of  the  old 
mill  have  lieen  re-modeled  to  use  flotation;  and  a  third  section  is 
!!!sw  iie.'ii'lv  re.'iilv  Tlie  i^iill  1*^  beii^.f  ve-!ti.'^fb^le;l  ,i  ^".-^f :.".?'.  sf  ;: 
time  by  the  coiii|)an.v's  engineering  dei)arfment.  Some  remarkably 
rapid  work  has  been  accomplished  in  changing  over  from  one  system 


ll.oTMloN     \1'   Tllr  :\V  \>1I()K  HKDI'CTIns    \\iHiK>,    \\\'i)M)\  IH!! 


110 


TMK    FLOTATION    TKOCKSS 


In  tlir  iitli.r.  For  iiislaiicc.  tlic  No.  -2  s.vti(.ii  t<(  tlic  nill  w.is  Jii 
(iprratidii  <iii  till'  2(;ili  (lay  of  .May  for  oniiiiary  wat.Tcoiicciit ration  ; 
liiit  w.xs  wholly  ir-<'()iistruitf(l  and  in  oi.crat.(;n  usinir  tlic  tlotation 
pnxTss,  on   til.-  L'titli  .lay  .)f  June.      Ka.'li  sc.-ti..n   lias  a  .'apariiy  .,f 

2000  tons  of  orifjinal  f 1  daily.    At  the  [iivscnt  rate  of  rf-i-oiistni.ti..n 

the  entire  ])lant  will  li.'  remodeled  liy  January  1.  lOKi. 


FLOTATION  AT  THE  CENTRAL  MINE,  BROKEN  HILL 

Jiy  James  IIeubakd* 
(From  the  Mutimj  (IikI  Siiriilific  I'rrss  of  SeiitcmluT  4.  1915) 

vHaki.y  Attkmi'ts  at  Fuothino.  Whih-  eoii.'entratin^r  the  galena 
in  the  lead  ore  produced  from  the  Central  mine,  a  valuable  by-product 
was  obtain. d  in  the  form  of  sliine  assaying,'  l^-;;  lead,  20'i  zinc, 
an.l  IG  oz.  silver  per  ton.  This  came  from  an  ore  in  which  quartz 
and  rho.lonite  were  the  chief  ganfnu'-minerals.  In  the  course  of 
ordinary  operations,  it  hail  long  been  observed  that  a  froth  was 
formed  .oiitaininf,'  high  metallic  values,  in  silver  and  lead  par- 
ticularly, whcn.'ver  conditions  were  favorable,  as,  for  instance, 
where  the  rotation  of  tronimels,  or  the  splash  of  the  elevators  or 
rart'-wheels.  or  the  motion  of  the  jig-plungers,  produced  a  violent 
agitation  of  the  mill-water  containing  sliine.  Early  in  1901  a  series 
of  experiments  was  carried  out  for  the  purpose  of  rc^iroducing  and 
accentuating  the  conditions  responsible  for  this  valuable  Hoat- 
concentrafe.  Experiments  and  t.'Sts,  exten.ling  over  several  months, 
were  made  on  slimes  of  varying  degrees  of  tinenes.'s.  Among  the 
appliances  tried  was  a  series  of  funnel-shaped  vessels  with  the  small 
enils  downward,  each  fitted  with  an  overflow-lip.  The  bottom  end 
of  the  funnel  or  cone-shaped  vessel  was  fitted  with  a  tap  or  plug 
.iischarging  the  contents  into  the  next  ves,sel  in  the  series,  and  so  on. 
To  each  vessel  w.-is  attached,  near  the  bottom,  a  water-pipe,  as  well 
a.s  a  pipe  carrying  compressed  air.  The  object  of  the  water  was 
to  provide  an  upward  current  for  the  contents  of  the  vessel,  while 
the   object    of   the    compressed   air   was   to    produce    agitation,    and 


•Manager  of  ttie  Central  Mine,  Broken   Hill,  New  South  Wales, 
tAbstractof  paper  appenriiiK  in  the  Proceedintrs  of  the  Australasian  Insti- 
tute of  Mining  Engineers.  November  10,  191:?. 


KI.UIATKiN    AT    Tin;    CKNTHAI,    MINK,    llUnKI  \     Hill. 


II 


t'lihuiicf  the  iiKitiitidri  frtVrt  of  tlic  iip-t'uiTtiit  of  wiittT.  in  the 
cxpcc'tutioii  of  rfproiliiciiif?  tlie  <'oii(litioris  (■aiisiiip  the  'tloat'  or 
iiiftiillic  froth.  Spcakiiit;  frincrally,  thcso  i,-.\peri incuts  were  on  the 
lines  of  a  spitzka.sleii,  with  a  stroiif,'  up-current,  to  produce  an 
apitatioii  of  the  slime-watiT,  iussisted  l>y  jets  of  ec.mpressed  air.  It 
was  thus  early  reeopii/,.,1  that  flic  Imhhles  of  froth  noticed  in 
tin  \vct-(!oiic<>ntrHtion  o|>cralioiis  wen-  due  to  the  aeration  produced 
hy  violent  atritation.  resultiiifc  from  mechanical  implements  moving 
rapidly  in  water.  In  these  experimcins  a  metallic  froth  or  scum 
could  he  produced  and  recovered  assaying  2C,  oz.  silver,  W',  lead, 
and   L'L";    /inc.      The  appliMiicc   employed    is  illustrated    in    rig.    ]!», 


FlO.    19.       APPARATU.S   lOB   KXPEBIMENTS   ON    KROTII. 

[Up  to  that  time  the  lead  concentrate  was  the  only  marketable 
proiiuct  from  the  ordinary  water  concentration.  Besides  calcite, 
the  ore  contained  a  good  deal  of  rhodonite  and  garnet,  each  of  which 
ha.s  a  si>ecitic  gravity  close  to  that  of  blende.  Thus  water  concentra- 
tion could  only  yield  a  quartz  tailing  and  a  leady  zinc-rhodonite- 
garnet  middling.] 

Preliminary  Test.  Pearly  in  ino,3  an  exhaustive  series  of  labora- 
tory tests  was  made  on  the  lead  by-product  by  flotation  methods, 
using    heated    sulphuric    acid    and    salt-cake    solution.      These    tests 


112 


Till'.    KI..)TVT|iiN     I'UiMKss 


viildfd  sdiii.'  .sli^'hi  iiifiLsiiiT  111  sui'i'i.ss  on  iiialriial  s|nriallv  |»iv|)aiiMi. 
that  is,  oil  jjniiiiy  niat.Tial  I'mm  uliidi  Imtli  the  nnivsi-  and  liiif  liad 
Ikiii  •■liMiinat.cl.  I.avmt,'  it  r\,n]y  si/fd.  Crrtaiii  cla.vs.'s  of  ih,' 
iiialirial  produced  lj\  our  miils  contaiiii'd  .smii  a  iar>;f  proportion 
of  iarl.onat.'s— siidi  as  carlionalis  of  iiiarijfaricsc,  linif,  and  lead- 
that  no  HotatioM  eoiiM  lie  secured  e\(i>pt  by  a  prohiliitive  eonsuiii|)tioii 
of  acid.  These-  tests  uere  ear-'fullv  made,  hut  the  l»est  work  done 
in  tlie  ialioratory  was  not  equal  to  liiat  liein>r  secured  on  a  I'onnnercial 
scale  in  the  existiii-,'  niat,'iietic  plant  The  tests  on  these  llnlatiiui 
iMclhods  were  conduclel  in  pans  or  vessels  worked  on  the  prM|,.ipl,.s 
of  spit/kasleii,  follouirif,'  the  lines  of  Potter  and   Dilprat.     \\<     lirsi 

ai>i)aralns   was   islructed    so   that    the    li(|uors  could    he    raised    in 

teitiperature  hy  liic  ai)i)lication  of  direct  heat  underneatii  the  |)aii  ; 
I'l'l  i"  the  later  tyi)es  the  teMi|)eralure  of  the  lirpior  in  tiie  pan 
or  si)itz  1)()X  was  niaintained  hy  the  injection  of  live  steam  into  the 

storairc  tank.      In    noi f   these    tests   was   aj;itation   employed,    the 

material  to  he  treated  heintr  fed  practically  dry  on  the  surface  of 
the  liipior  in  a  rci^ular  stream,  and  the  heated  liiiuor  added  through 
a  pipe  diseharf,'inf;  near  the  hottom  of  the  vessel,  and  given  an 
upward  inclinalion  in  order  to  produce  an  u])-eurreiit  in  the  ho.x 
it.self  and  a  gentle  overflow  at  the  lip.  A  still  surface  was  imperative 
in  this  operation,  and  it  was  eipially  evident  that  the  operation 
de])en(h'd  largely  I'or  its  success  on  surface  tension  of  the  liipior. 
after  the  gas  evolved  hy  the  action  of  the  acid  on  the  mineral 
earhonates  had  raised  the  particles.  This  surface  tension  was 
increa.sed  hy  the  density  :ittained  in  the  one  case  hy  the  salts  formed 
from  the  mineral  and  gangue  through  the  action  of  the  sul|>huric 
add.  and  in  the  other  hy  the  addition  of  salt-cake.  In  all  tlie.se 
experiments  the  licpior  was  returned  hy  the  ordinary  type  of  air-lift, 
using  compressed  air  at  ahout  70-lh.  pressure.  These  experiments 
dednitely  demonstrated : 

1.  That  there  was  a  limit  to  the  size  of  the  particle  that  could 
he    buoyed   Up. 

2.  That  any  material  below  a  certain  size,  no  matter  what  it.^ 
character — whether  gancue  or  mii\eral  -floated,  owing  to  the  density 
of  the  solution. 

•"?.  That  if  the  finer  particles  of  gangtie  were  not  eliminatci] 
hefore  treatment  they  wotild  be  floated  with  the  mineral,  and  lower 
its  vnliie  in  metnls  to  sncn  an  extent  S.i  to  m.lke  it  ii;i!n.Tr!ci^t;d'.!c 

Slime,  whether  existing  as  a  by-product  of  the  ordinary  wet-mill 
concentration    or   subsequentl.v    produced    in    preparing    tailing    for 


:j^^  ■.. 


1  r,(PT\TliiN     AT    Till,   (  KNTKM,    MINK,    HHUKKN     Mll.l, 


ll;i 


tnatni.'iit,  l.iilkcd  so  Utrarly  iiiiioiij.'  tli,.  total  iriatrrial  availalil.^  for 
n-tr,.atnu'iit  that  any  pro-'css  that  lail,.,|  ii,  this  dinctioii  was  too 
limiti'fl  in  its  wop,,  to  \,v  of  iiiiK'h  vahic  to  lli..  Central  iiiiiic. 

As  far  as  unv  process  up  to  .late  was  .•onceriicd.  slitni'  had  to 
lie  reiranled  as  of  no  valiif  exeept  in  so  far  as  it  was  availahle  for 
siiieltintr.  Th..  Hroken  Hill  I'ro[)rietary  Co.  had  used  a  eousi.lerahlc 
•luaiitity  in  this  way.  and  ha.i  diseov.red  that  roastini;  or  sin- 
tPrinir    the    slime    in    open    heaps    after    hri(piettin>r    ^'ave    a     fair 

[)ro(lPet    valiial.le    f(,r   snieltin(r.   ..;    ,^ i   ,|,.„|   „f   ,i„,   sulphur   an.l    a 

fair  proportion  of  the  zinc  havini;  hccn  driven  off.  The  Suli)hi(le 
Ccrporntion  also  souplit  to  inak.^  its  slime  avaiial.le  hy  this  m.^ans, 
hut  it  Wius  proved  that  the  losses  of  metal  were  too  ^freat  to  .ju.stify 
this  method  of  rendering  the  slime  amenahle  to  direct  smelting. 

Cattkk.voi.k   ok    (Iimm  i.atio.n    I'hocks.s.      The    forepoiup   experi- 
ments   were    aliandoned    on    account    of    information    received    from 
London.      C.    F,    Courtney,    wlio   was   in    Knsjland    durinkf   the   year 
1002,  adviwMl  that   a  discovery  of  eonsideralile  importance  had  been 
made:  that  laboratory  trials  gave  every  indieation  of  success  on  a 
larprr  scale:  and  that  the  process  was  so  comprehensive  as  to  include 
the  finest  slime  and  varying  coarser  sizes  of  particles  up  to   \  mm. 
diam.     This  wa.s  .subsequently  known  as  the  Cattermole  or  granula- 
tion  proc'ss,  and  eonsiste<l  in  the  agitation  of  a  mixture  of  pulp, 
oil,   ami   water,  containing  a  suitable   acid,   or  an   alkali   with   .soap 
or    (>ther    emulsifying    agent,    so    as    to    agglomerate    the    oil-coated 
particles   into  granules.     Thi'  oil   was  thus  empi  'yed   in   a  state  of 
ennd.sion   in   water   in   the   pri'senee  of  an   emulsifying  a^ent,   such 
as  soap.     After  agitation  the  mixture  was  pas.sed  into  an  up-current 
separator  or  eliussifier  to  remove  the  lighter  non-oil-coated  i)articles 
from   the  agglomerated   mas.ses  of  oil-coated   particles.     The   lighter 
sand   having  been   eliminated,   tlie   pulp   passf^d   to   a  second   series 
of  agitators  to   increase  the  size  of  the   granules,   and  thence   to  a 
W'cond    classifier    for   the    removal   of   the   heavy   sand.      From    the 
bottom    of   this   second   clas.sifier   some    granulated    concentrat.^    was 
recovered,  but  the  heavy  sand  from  the  overflow  also  carried  over, 
with  the  up-currc.it.  a   large  amount  of  granulated   mineral.     This 
mixture   of   gratudated   mineral   and   h^avy  sand   pa.ssed   then   to   a 
Third  series  of  agitators,   and  thence  to  a  shaking  table,  where  the 
granulated    mineral,    rendered    more    buoyant    hy    directing    ipts   of 
compres.sed  air  onto  tlie  surface  of  the  moist  pulp,  was  buoyed  to 
the  .surface  of  the   water  and  floated  off   the   bottom  of  the   table, 
while  the  gangue  sank  and  was  delivered  over  the  end  of  the  table. 


114 


THE    FLOTATION    rROCF.Sri 


III  order  til  trivf  lliis  i)n>cfs.s  a  thoroiijjh  trial,  a  luodrl  plant 
was  soiit  from  Kii;,'laiul  ami  urcLted  on  the  mine  early  in  1904. 
(J.  A.  Chapman  was  specially  ajjpointed  to  conduct  experiments 
with  this  i)laiit.  and  started  a  lonj,'  series  of  tests  early  in  June  oi 
the  same  year.  It  was  (piiekly  demonstrated  that  the  process  was 
capai)le  of  makin-;  liiKh  recoveries  of  all  the  three  metals  from  the 
very  finest  slime,  whether  taken  from  the  current  work  of  tlie  mill 
oi-  from  old  accumulations,  and  also  that  old  t;iilin>r  oi-  new  crude 
ore  were  ainenable  to  treatment  when  crushed  to  a  jjiveii  fineness. 
The  largest  size  of  particle  that  could  he  recovered  was  ascertained 
to  be  about  \  mm.,  thus  conlirmini;  the  London  woi'k:  but  it  was 
found  that  results  improved  with  a  decrease  in  size  to  impalpability. 

Ill  the  eai'ly  tests  by  Mi-.  Chapiaaii,  emulsions  of  the  heavy  oil 
of  petruleuiu  were  used,  but  the  cost  was  excessive,  aim  it  was  found 
iinpos.sible  to  treat  slime  successfully.  Emulsions  of  fatty  acids, 
and  also  soft  soap,  were  then  tried,  but  proved  i)roliibitive  as  to 
cost,  except  in  tlie  case  of  o  ie  acid.  Oleic-acid  emulsion  was  found 
to  act  rapidl.v  and  etfectively  on  crude  ore  as  well  as  on  all  lead 
by-produi'ts,  includinn;  slime. 

Mr.  ("hapman's  work  on  oils  and  the  results  obtained  by  him 
with  the  model  plant  usinrr  the  grranulation  process  were  satisfactor.v, 
but  it  was  thought  wise  to  have  these  continued  by  an  independent 
chemist,  and  therefore  ,1.  C.  Moulden.  the  company's  chief  metallur- 
gist at  Cockle  Creek,  was  called  in,  repeated  the  exjteriments.  and 
amply  eonlirmed  ^Ir.  Chaiunan's  work.  Later  it  was  found  possible 
also  to  reduce  the  )|uantity  rl  oleic  acid,  as  was  jtroved  by  the 
follov  iiifr  tests  in   December  "l!l04: 

Material  ust'd  was  ciMished  tailintf  mixed  with  slime. 

Test  No.  1.  ;{..")'■;  oleic  acid  on  min(>ral  and  f*.?")'','  sulphuric 
acid  circuit. 

The  cost  of  emulsion  in  this  case  was  10s.  per  ton  of  ore.  but 
the  renalts  were  excellent,  the  concentiate  lieing  rei-overed  as  partly 
granulated  and  j^artly  float  or  froth. 

In  test  Xo.  2.  only  0.75';;  of  oleic  acid  with  th(>  same  ((VTo'/e ) 
sulphuric  acid  circuit,  in  which  Ciise  the  <'ost  of  emulsion  amounted 
to  2s.3d.  per  ton  of  ore.  the  results  being  excellent,  with  idl  float 
coneenlrate.  no  granular  ma'erial  being  formed.  This  test  took 
considerably  longer  in  agitation. 

EiuccTioN-   (IP    Lah<;f.    Plant.      Mr.    Cliapman's   tests,    and    their 

ft'as  n)){;tin*'ii  tli.'it    wduM.  witii   siiitaitic  ni'raiigomonts  fui-  cnisliitiff. 


FLOTATION    AT    TllK    CKXTHAI.    MINI;,    BHOKKX    1111, 1. 


11.') 


efficii'iitjy  handle  the  wiiole  of  tlie  by-products  of  the  -vet  mill, 
including  slime.  It  was  accordingly  decided  to  erect  a  plant  on 
the  lines  of  the  model,  with  slifrilt  modifications  a.s  dictated  by 
experience,  capable  of  treating  100  tons  per  day,  operating  on  a 
commercial  scale. 

It  was  clear,  from  experimei-ts  and  oliservations.  that  the  time 
of  agitation  was  a  factor  in  tiie  aeration  and  oiling  of  the  mineral 
particles.  Therefore,  reckoning  [  'im  ijic  size  and  capacity  of  the 
mixers  in  the  model  j)lant,  a  mixer  was  built  of  the  following 
dimcn.sions:  .">  ft.  deej)  and  :$  ft.  diam.,  with  a  \\ooden  stirrer 
2  ft.  6  in.  diam.  at  bottom  placed  vertically  and  made  to  revolve  at 
the  rate  of  350  r.p.m. 

Experiments  with  this  one  mixer  unit  indii'ated  that,  to  make 
the  treatment  continuous  for  the  stipulated  100  tons  i)er  day,  it 
would  be  necessjir>'  to  have  for  the  first  unit  a  series  of  six  mixers 
in  order  to  allow  of  the  proper  cleaning  of  the  particles  and  the 
thorough  aeration  of  the  whole  mixture  before  the  discharge  of 
the  material  under  treatment  from  the  last  of  the  series.  Tiie  mixer 
was  of  the  core-stirrer  tyi)e. 

Accordingly,  the  plant  was  designed  on  these  lines,  and  con- 
sisted of: 

1.  Grinding  ap])aratus. 

2.  ^■at  for  emulsifying  various  oils, 
•i.     Set  of  six  mixers  in  series. 

4.  l'pca.sts  for  separating  .sand  and  float. 

5.  Second  set  of  mixers  for  further  aeration. 

6.  I'pcasts  for  further  s<'paration  of  sand  and  float. 

7.  Third  set  of  mixers  far  re-aeratioii. 

8.  Wilfley  tallies  for  the  separation  of  coarse  sand  from  granu- 
lated, sulphide. 

Early  in  190.")  the  construction  of  this  plant  wa.s  commenced;  it 
was  completed  at  a  cost  of  £]  1.000,  and  .started  work  in  July  1905. 
The  method  of  treatment  adopted  was  on  the  lines  of  the  tests  made 
i'l  the  experiemental  modid  plant,  and  may  he  briefly  described. 
See  Vig.  20. 

The  ore,  reduced  to  a  suitable  fineness,  was  elevated  to  a  ho])per 
at  the  top  of  the  Iniilding  and  id  into  No.  1  mixer,  where  it  was 
agitated  with  the  solution,  the  emulsion  (previously  j)repared  on 
the  bottom  floor)  being  added  at  t!ie  .same  time,  together  with  further 


addition  of  i 


VI,  11   ni(iuieu.      1  lie   leed  iii    ground  maicriai   and   tne 
le  circuitdiqiiiir  and  reagents  was  maintained  constantlv 


lUi 


■I'lIK    ri.iiTATlciX    l'li()(K>S 


iiiiii  rcguhirly.  Aftrr  passin^r  lliri)ii.u'li  tlic  first  set  nf  six  niix.Ts  a 
pulp  consisting  of  jrniuiul  oit,  acidnlaicd  wat.r.  an,]  .iiiiilsioii  was 
j)asse(l  to  a  iiydraiilic-si/ini.'  a])pliiiMcc  known  as  an  upcast.  wIkt" 
the  slinic-frau'.'iie  was  cliininat.Ml  hy  ovcrtlowintr.  Tin-  lialaiirf  of 
tile  MMxtnn-  was  passed  into  tile  second  siM  ot'  mixers,  liejrinnin^'  with 
X".  7.  where  more  eiindsion  and  snlpimrie  acid  were  ad(h-d  if 
necessary.     The  afritation  and  aeration  were  maintained  and  tiie  imiIi) 


rj-- 


I  ^^ :"-'^<"(l J 


T        I 


LCm:'^  rcuR  ■iimrt-. 


ll 


A — ^ 


.,^^-;:=r::d_J 


—^ -|&*1    ^\  F  R  5UMP^  1 


Fi(i.   20.        inK    KXTKRIMKNTAI.    MeUKI.    I'J  A  NT. 


dis,-har!.'ed  fiom  .\o.  I»  into  anotiier  upcast,  wiier.'  further  slime- 
jran-ue  was  eliminated  hy  overflow.  The  haiance  of  the  material 
was  then  i)ass<Mi  to  No.  10  mixer,  and  thence  throu^'h  Xo.  12  to 
the  Wiitley  tables.  The  .sejiaration  on  the  tallies  was  etfected  thus: 
Such  concentrate  as  had  hecn  frotheil  by  the  aeration  and  a.L'italion 
passed  oir  the  table  immediately  ojiposife  tli,-  point  of  fei-dintr.  The 
irranulatcd  or  'air-bally'  nmterial  remaiuct  in  dosi  contact  with 
the  table.  ah.n>r  with  ih,.  sand,  but  tloatd  inniiediately  under  the 
intluenee  of  iJufTs  of  air  'supi)lied  throufrh  a  pipe  l;iid  lentrthwi.se 
ami  close  to  the  tahh".  and  then  floated  off  with  the  froth  <'om-,.|itrate. 
'i'he   san.i    was  delivered    toward   and   at    the   end   of   th,'   table,   thus 


ri.ilTATIdN    M    TlIK   CKNTHU,    .MINI:,    liKDKKN     1111. i 


11 


exactly  reversiiif;  tli.'  it'lativp  positions  of  coiuvntrate  and  tailing 
as  tmlinarily  oi)taiiiril  if  workinj?  hy  fjravity  eoncuiitration.  Tlio 
sliiiio  and  .iid  were  lollci'tt'd  in  one  rcc-ptahlc  and  tlie  float  and 
^rj.nulatcd  cniifi'Mtratc  in  another,  tlic  .surplus  li(niors  in  each  case 
flowiiijT  to  a  coiiiinon  suiii|)  for  re-iisc. 

From  the  tirst  day  of  oi)eratioti  the  ease  with  which  the  float 
concentrate  couhl  he  reeovei-ed  was  very  sti'lkinfr;  hut  the  separation 
of  the  "ranuiated  concentrate  from  the  coarse  sand  hy  tabliiifr  on  a 
larfic  .scale  was  found  to  lie  a  ver\  delicate  and  difficult  operation, 
and  it  was  at  once  evident  that  'spitz'  separation  would  relieve  the 
tallies.  The  upcasts  were  also  continually  chokin-^  and  pi-oving  a 
soi.ree  of  trouhle.  besides  seTidintr  over  larp'  (juantitics  of  slime 
with  the  eoncentrate.  thus  rediicinpr  the  f;rade  of  the  product  and 
les.seninfr  its  market-value. 

It  was  therefore  decided,  when  the  i)Iant  had  been  runniiifj  for  a 
few  days  only,  to  construct  a  small  rectaiifrular  s])it/,-l)ox  for  trial. 
This  was  introduced  early  in  Autrust  190"),  the  feed  to  the  spitz-box 
beinp:  prepared  i)ulp  di.scharfred  from  No.  7  mixer. 

Tt  was  found  also,  as  soon  as  t!ie  plant  started  rpjrular  treatment, 
that  the  au'italiou  was  exces.sive.  and  mixers  10.  11.  and  12  were 
cut  out. 

fone-a^itators  made  of  phosphor  broitzi>  were  tried,  then  cen- 
trifufral  stirrers,  but  the  scour  both  on  the  stirrer  and  the  sides  of 
the  ini.xcr.  due  to  the  impact  of  the  sand,  was  so  fjreat  that  these  liail 
to  be  abandoned,  althoufjh  the  afritation  and  aeration  had  been  con- 
siderablv  increa.sed. 

The  spitz-box  in  the  slime-overflow  circuit  pfave  excellent  result.s. 
and  toward  the  end  of  August  it  was  pos-sible  to  obtain  the  requisite 
aoritation  by  usinjif  the  first  six  mixers  oidy.  A  fre.sh  spitz-box  was 
placed  in  'he  position  formerly  occupied  by  vats  7  and  8,  with  ar- 
ranjrements  for  all  tailinfr-flows.  both  .slimes  and  sands,  to  deliver  to 
No.  1  hutch  of  a  special  spitz  on  the  floor  beneath.  The  ob.ject  of  this 
spitz  Cl-compartment'i  was  (11  to  allow  a  settlement  of  the  granu- 
lated material  in  the  first  compartment;  ('2)  to  etfcct  a  s»>ttlement  of 
middling  for  re-treatment  on  tables  in  the  second:  ('■])  to  provide  for 
Hie  deposition  of  clean  sand  and  slime  in  tlie  third,  with  an  un- 
restricted overflow  for  the  float  material.  Spra.vs  on  the  surface  of 
the  liquor,  and  upcasting  ,iets  of  water,  were  provided  to  assist  the 
operation.  Various  simplified  fi>nns  were  later  adopted  as  the  process 
merged  from  partial  to  complete  flotation,  as  illustrated  in  the  ex- 
perimental spitz-box  for  the  granulation  plant   (Fig.  211. 


118 


TIIK    H.OTATION    PROCESS 


At  tirst  tho  san.i  was  cj.rted  l.y  sluiri,,-  out  to  a  daiii ;  hul  lliis 
beiiif,'  wasteful  of  circuit-li.iuor,  ,,n,i  tlicivfor.'  also  add,  it  wm.s  de- 
cided to  construct  saiid-box.s.  throu-li  wliid,.  i„  turn,  tho  suspondrd 
sand  could  be  deposited— tlio  li(iuor  ovcruowinjr  from  tliesJ  .sand- 
boxes to  be  ran  to  the  puiiip-sunq,  and  thence  re-eireulated  through 
tho  plant.  By  this  moans  a  eh.sed  eireuit  would  be  secured,  and  li(iuor- 
losses  minimized.  It  was  not  until  November  that  those  sand-boxes 
were  actually  in  use.  Meantime,  it  was  noted.  partirMdarlv  in  slime- 
tests,  that  the  operation  was  ai)preciably  assisted  bv  laisinsr  the  tem- 
perature of  tho  liquor.  Steam  jets  were,  tliorefore.  introduced  into 
the  mixers  m  the  plant  early  in  .Septend)er  IDO,'). 


Fig.    21.      KXPKUI.ME.MAI.    .sIMTZ-1 


Before  advancing  further  with  the  evolution  of  the  process  as  de- 
v.lnped  in  the  first  large  plant,  it  is  perhaps  advisable  to  refer  here 
to  certain  experiments  that  mark  a  most  important  era  in  the  hislorv 
of  the  process. 

DisrovKKv  (.F  TIIK  FmrriiiNG  I'liocE.-^.s  We  now  com.>  to  a  stage 
when  a  remarkable  development  in  the  operation  was  discovered 
(Strangely  enough,  at  tho  same  time  both  h..re  and  in  the  Patent 
Co.  s*  laboratory  in  London^,  which  had  for  its  main  principle  the 
reversal  of  all  previous  oi.erafions.  and  consisted  in  the  complete 
flotation  of  each  i)Mrticle  of  min.-ral  independently  in  place  of  granii- 
bitmg  tho  mineral  partb-les  and  causing  them  to  sink,  thus  not  onlv 
revolufieni/ing  th,"  pro,-,  s.s.  Im.I  gieally  .simplifying  .•,nd  cheai.enin-  it 
Ihe  dovelopuH-nts  noted  were  mainly  along  tho  line  of  decreas,.,!  con- 
sumption of  oleic  aci,]  or  oil.  for  example,  from  'V,  oleic  on  ore  ro- 
suinng  n.  very  little  float,  down  to  1';.  .^riving  pracficallv  a  complete 
float. 

Th<.  I^illowing  data  from  a  n  |M,rt  furnish.,!  hv  A.  li  Hi.-<rins 
w^<.:    ..   :v.  1. ■::.!..  iri.ii,  „T,-  i,,  niore  deiaii  liie  nature  ot  the  "xperi- 

*[Minerals  Se|i,-iration  Ltd.— KiiiiOR.l 


FI-OTATIDN    AT  TIIK  (KNTK.M,    MINK,    HKdKK.N    IlII.l. 


lU) 


iiifiits  jitid  thf  cffpot  oil  tlic  scpiinitidii  ^.i-ndiu'cd  by  v.iryiiitr  the  prr- 
iMiitagi-  of  oh'ic  acid. 

Dktaiis  of  Exi'kkimk.nts 


Time 

Pficcraatjo 

for 

Temiipr- 

\fi(l, 

Olfir, 

of  olfir 

;i  ('ration, 

aturp, 

% 

c.c. 

on  ore. 

niin. 

r. 

Remarks, 

1.1 

15 

u.'* 

t 

.■iO.o" 

Very  little  float 

1.1 

7.5 

l.r, 

■1} 

31.0° 

Rather  more  float 

1.1 

r..2 

1.04 

i; 

31.0" 

Still  more  float 

1.1 

3.i 

i>i\2 

t'l 

32.0° 

Still  more  float 

1.1 

l.CG 

ii.:;2 

t 

:ii.n° 

Float  vastly  increased 

1.1 

0.5 

(1.10 

s 

31.0- 

Float  vastly  increased 

In  (ncry  cjiso  the  oleic  jicid  has  lieeti  tncasuied  iii  cubic  centimetres 
and  the  peiTPiitapcs  calculated  as  thoiifrli  they  \veif;licd  grains;  hut.  a.s 
the  .specific  gravity  of  oleic  is  less  than  that  of  water  (taken  a.s  1),  all 
perci'ntages  will  be  lower  than  those  actually  priven. 

These  experiments  obviously  proved  that,  the  r(>duction  in  the  per- 
centage of  oleic  acid  materially  altered  the  type  or  character  of  the  oil- 
ing 'if  the  mineral  particles — the  higher  percentage  proilucing  gran- 
ules, which  were  precipitated,  while  the  lower  percentages  produced  a 
mineral  froth.  As  the  qiuuitity  of  oleic  acid  decrea.sed.  tlie  time  re- 
quired for  oiling  th.c  mineral  particles  and  aerating  them  was  found 
to  increase,  and  tnorti  froth  formed.  These  tests,  followed  by  niiuiy 
others,  led  to  Sle.ssrs,  Sulnian.  Picard,  and  Ballot's  Britisli  patent  of 
April  12.  irtOS,  under  whicli  "finely  powdered  ore,  suspended  in 
acidified  water,  is  mixed  with  a  small  proportion  of  an  oily  sul)stance 
such  as  oleic  acid,  amounting  to  a  fraction  of  1<~J  on  the  ore,  and 
agitated  until  the  oil-coated  minerals  form  into  a  froth,  which  can  be 
separated  from  the  gansue  by  flotation.  Heat  may  be  applied  to 
facilitate  oiling,  and  either  shaking  tallies  or  spitz-lioxes  may  be  used 
to  separate  tiii>  frotliy  mineral  from  li.e  sands  and  tli<>  gaiigue  slime." 
To  return  now  to  the  record  of  operations  at  tlio  large  plant,  some 
successful  te.sls  were  carried  out  in  September  100.')  on  dump-slime, 
by  using  this  flotation  method.  Agitation  nas  conipl(>tcd  in  six  mix- 
ers (using  cones)  in  0.6  to  1%  sulphuric  acid  at  a  temperature  of 
•'"'''"'  !■'  Til"  ipiaiitity  of  oleic  aeid  used  in  these  tests  was  from 
dl.")  to  n.L";  on  the  actual  dry  wi'ight  of  slime  treated.  From  the 
sixth  mixer  the  pulp  passed  "with  a  good  splash"  to  ilie  first  .spit?;, 
and  iiie  residues  from  this  "with  a  good  .splash"  t"  No.  2  spitz,  and 
the  tailing  from  this  latter  spitz-box  was  run  into  lains,  Tiiese  and 
otiier  experiments  emphasized  the  import mee  of  dropping  the  pulp 


? 


120 


THE    KIX)TATIUN    I'ROCESS 


vertically  into  tlif  spitz  to  assist  amiti,.,,  aiwl  sul,s,.,,iu.Mt   Hotation 
aihl  j)t  liuatui-  tlif  li.HK.r  to  enhaiav  tii,.  ..ili,,,;  of  .niiuTal  partirlrs. 

'Ill-  liuvr.,-oiii])artiii..nt  spitz-l,ox  with  upcast  wator-tlows  -ave 
!'I.-H'.-.  ill  luni.  to  a  t\v.,-,.ompartme.it  spitz-hox  witiiout  upcast  flow 
and  tins,  in  turn,  was  replact-il  t,y  a  sin-l.M  onipartincnt  spit/  tin' 
latter  Ih.ii,^^  provide.!  with  a  rijji.l  flat  hoard  on  which  the  I'cod  was 
splashed  to  assist  aeration.  Conieal  si)it/.-hoxes  were  tried,  hut  not 
jreiierally  adopted. 

From  Oranilvtiu.v  to  Fr.oT.vTioy.  The  plant  had  now  hcen 
ni.inin-  tor  a  .■nuple  of  months  on  tailinirs  and  slimes  from  various 
sources,  and  durin-  this  time  the  frothin-  method  was  senerallv 
ousting  the  crranulatiou  pro.-e.ss.  until,  tinally,  the  .superioritv  of  the 
spitz-hox  and  froth  method  was  clearly  demonstrate,].  The  Wilfley 
tallies  of  the  original  plant  were  then  dismantled  to  make  r.Mmi  lor 
the  sand-hoxes  already  mentioned,  and  the  frranulation  <rave  wav  to 
flotation  with  simple  spitzdn.xes  early  in  October,  after  treatment  of 
approximately  1700  tons  of  .-nnle  ore.  tailintr.  and  slime. 

Tins  method  of  working,  thus  briefly  (,utliued.  quieklv  established 
it,s<>]f  as  capable  of  dealing  with  the  company's  ores  and'bv-pro.biets 
and  :\rr.  Thapman's  patent  of  September  1006  was  taken  out  to  pro- 
tect the  various  di.scoveries  made  by  supplementing  Sulman    Picard 
and  Ballot's  patent  (No.  r,0.32.  Vmy    T'ndcr  .Mr.  f'hapman's  patent:" 

1.  The  ore.  suitably  crushed,  is  agitated  with  acidifi,.d  water  in 
the  first  mixer  and  heated. 

2.  Oleic  ai'id  is  sub.sequently  add,   1  in  the  secon.l  vessel. 

■3.  The  pulp  is  maintained  at  the  desired  temperature  in  the  third 
and  following  mixers,  with  violent  agitation  in  each  mix,>r  to  insure 
comph't,.  and  thorough  aeration.  A  s.^quence  r,f  operations  is  thus 
arranged  by  which  the  s,)]ution.  after  the  secon,!  au'ilat,.r.  is  pra,- 
ti.^ally  or  entirely  neutralize,!,  so  that  the  liquor  in  circuit  as  a  whole 
IS  neutral,  .'xcept  at  the  mitset.  when  the  ore  is  introduced. 

Th,.  a,],)ption  of  this  flotation  pn.cess  with  its  neutral  li.pior  al- 
lowed the  use  of  iron  where  formerly,  under  the  granulati,.n  inetho,!. 
with  aci,!  liquor,  oidy  won,!  or  special  metal  ,'ould  be  used.  For  in- 
.sta.H'c.  the  original  w<ioden-eone  mixers,  which  had  been  replace,!  by 
cenlnfugal  stirrers  of  copper  or  beaters  of  regulus  metal,  w.-re  n„w 
r,'i)lace<l  by  fimr-arme,!  stirri'rs  of  east-iron. 

A  great  ,!iificulty  lay  in  the  grinding.  The  exp,'riments  had 
pr,ivc,]  that  the  best  work  could  b,.  obtaine,!  on  mat,Tial  that  wouM 
pa,s.s  ii,r,mgii  40.me,sii.  an,l  that  pra,-ti,"ally  the  finer  the  material 
the  better  the  recov.'ry.     The  whole  experience  in   th,.   flue  crHn.lin- 


I  I.l.TATK.N     \T   TIIK   .      \t|(a1.    MINK,    HHUKKN    1111,1. 


121 


lia.l  hcoM  uith  hull  nulls  ,n  our  nu.-'MHi,.  plant,  an.l  arc-nlinfe'lv  a 
No.  8  Kru,,p  dry  hall-null  was  allarh..,!  i„  ,l,is  plant  .us  part"  .,f 
tlH-  .■.pnp.ncnt.  Tl,,.  dry  n.ill  pn.v.d  unsuitabl,.,  an.l.  wtl.  consid.r- 
abk-  dith.ulty,  a  was  converted  to  a  wet  mill.  Kvn  ti,..n  its  ,-apa,.itv 
allowiDg  tor  nunu.rous  break-downs  partly  ,h,.-  t,.  lorcing  its  eapacitv' 
was  too  limited,  and  two  No.  :,  Knipp  wet  ball-mills  were  install,;! 
to  assist.  Meantime.  ..x,K.rimen1s  proved  ■•onehisivelv  that  -rindini;- 
rans  were  superior  in  eliara.-t.r  of  work.  ...st  of  inaintenaMee  and 
l.ower  eonsmne.1,  to  the  l,a]l-mills  for  ro-^rrinding  tailing,  whereupon 
we  in.s  ailed  a  gr.mling-plant  whieh  was  gradually  inerea.sed  until 
t  u-  ball-mills  were  thrown  out  of  use  entin-lv.  Th-  ehara-ter  of 
the  work  was  mueli  improvrd,  and  it  was  then  evident  how  much 
1.0  progress  ot  the  pn.ee.ss  to  a  s^itisfaetory  stag,  of  efiieienrv  had 
been  retarded  by  lack  of  eflfieient  grinding  applianees 

KxTKN.io.v   „K    1T..VXT.     The  operations  of  th..   first    plant,  were 
-MMiereially    and     teelmieally    sueeessful.    ami    an    extension     was 
completed,  with  all   its  appurtenances,   including  grind.ng-p«ns   for 
the  re-luction  ,.f  the  material  to  the  requisite  degree  of  comminution 
conveyor-belts  tor  the  .lisposal  of  the  residues,   together  with   bins 
for  concentrates  and   tanks   for  stor,  ge  of   liquor,   toward   the   end 
of  1006,  at  a  cost  ot  £2,1,000,  the  sum  of  £11.000  having  been  already 
spent    on    the    initial    experimental    plant.      The    total    .|uantitv    of 
material    treated    by    this   flotation    plant    was    KJo.SOS    tons     which 
yielded    4:..147    tons    of    higli-grade    zinc    concentrate.      The    plant 
fOMtmued  n,  successful  operation  nnlil  the  completion  of  the  wet-mill 
zinc  section,  which    was  capable  of  supplying  the  quantitv  of  xinc 
eoneentrate   nnder   contract.      During    the    time    this   plan't    was    in 
operation  numerous  tests  were  made  with  a  view  to  increasin-  the 
aerat-on,  which  was  recognized  as  the  chief  factor  in  tlotation?  and 
at  the  sa  ne  time  lessening  the  mechanical  energj-  absorbed  in  aerating 
Among  these  may  be  mentioned  the  nest  of  centrtifuijal  pumps    as 
.  histrated  in  Fig.  22.     The  pumps  were  worked  in  .series    ea.T.  o'e 
•rawing  a   tailing   from   the   preceding  ,spit.   and   di.seharging   into 
the  m-x    sueeeeding  .spitz.     The  aeration  and  flotation  were  produce,! 
satisfactonly    but   it  was  soon   found  that  the  scour  in   the  pumps 
caused    by    th,.   gritty   nature   of   the    matenal    being   pumped,    w's 
s-    ;..cat    that    th,.   !„.avy   maintenance   would   counter-act   the   other 
advantag..s.     An,.ther  expedient  was  to  lift  the  whole  of  the  tailing 

discharged  from  the  first  cr.;fv  »>„ _i.  .        ■    ..».       _.  .         ^ 

....  •  »      ■■-.-....   w,.   ai»  €*ir-iirt.      i  ins  aiso 

result,.,!  m  increas^Ml  aeration,  but  it  was  found  that  the  volume  of 
iHinor  would  have  to  be  increased  to  an  impracticable  quantity  to 


'    I 


12L' 


Tin;    FI.orvi-IoN    I'KCK'KSS 


jrivf  tlic  iirccssaiy  v.|n,-ity  to  cjirry  tin-  partidrs  <>\'  oiv,  rlc,  iqi 
tlie  risiii<r  Icir  ,.r  th,.  |,i|if  an. I  invvnit  sell  lini:.  An  drvalor  was 
siihsequoiitly  installiMl  in  its  pla.-r  to  cmninaiKi  111.'  tliinl  sj-itz  nl'  th,. 
series.  Fiii'llier  eNpedirnls  wiv  th,.  ins,.i.tinii  nf  a  j(.t  ,if  ;,ir 
into  a  ,-,.ntrit'iii,'al  i>iiiiip  us,.,!  I'or  i-aisinir  liiinors  and  iiiatiTi.-il  tor- 
re  tri.atirii.nl,   th,.    iiitr,),iiii.tion   ,it'  a   .i,.|    ,it'  i-,Hnpri.ssi.,l    air   into   th,' 


jr^t4-iy=kS=^y^.i  s  ■ 


Fig.  22.     a  nksi  of  (KMiiniiiAi.  n  mi-s. 


iiiixer-boxes,  an,l  al.s,i  the  ins,.;;i,)n  of  jiipi-s  in  the  ini.\er-lio.\,.s  in 
.smh  a  i)ositi,in  tiiat  air  wouhl  he  <ira\vii  into  the  lMitt,)in  of  tlie 
iiii.xer  liy  the  rotation  of  th,'  Ijiaders,  As  a  result  of  all  these 
e.\i>edieiits,  the  ,',in,'hisioii  was  formed  that  the  air.  to  lie  of  value, 
iiiiist  he  liiely  eonuuinut,',!.  tint  that  any  ad, lit  ion  was  ,if  vidue  that 
would  decrease  the  ein'rpry  rrquind  I,)  si'cure  ai-i'ation  liy  means 
of  mechanieal  atritatioii. 

:\IixKi{.\i.s  Si;i-.\i!ATiiiN  Pi.A.NT.  Til,'  .Minerals  Si-paralion  ,-ompaiiy, 
owners  of  the  froth  jiatcnLs.  ])ureliase,l  the  tailin<r-dumps  on  the 
Central  mine.  an,],  liy  arranueiiient.  a  plant  was  d,.si<,'ned  and  erected 
by  the  Sidplii,!,'  Cirporalion  for  th, '•  tn^alment.  The  ]dant  is 
slmwn  ill  I'l'dss-sei'timi  in  Fi?.  2:!.  ami  was  desitrned  on  previous 
e.\perieiice  for  the  treatment  of  2f)0()  tons  per  wi'i'k.  It  was  finished 
at  a  ,-ost  of  t;i'(J.000  ,.omp!ete.  The  ,.fti,.i,.n,.y  ,)f  th,'  j;riiiding-pans 
proved  .so  <,'rcaf  with  the  new  ,l,.si>rii  of  p,isitive  pan  that  the  plant 
wa.s  alile  easily  I,)  liamlli'  ."lOdO  tons  ]ut  W|.,'k.  This  p'niit  was 
respitnsilile  for  llie  Ireatiiu'iit  ,if  7<i!t.9|)!t  tons  of  tailiiifr.  etc..  and 
the  pr,ulu<-ti,.ii  of  242.402  tons  of  cmc'iitrate  iij)  to  the  tiiiic  it  was 
.slnit-,lowii  ill  .Tun,'   IIMI    on   tlie  ,'xliaustion   of  the  duin]).s. 

In  ,'oniii'cti,in  with  tin'  Miih'rals  S,'|iaralion  iilanl.  it  is  important 
to  note  tii/it  the  fai't  of  tjic  i.u'i'uit  heinir  iio  longer  le.-id  h'.it  ::;■■.•.< j.-.il 
has  been  taken  advantage  of.  inasmui'h  as  there  is  only  on,'  ,'ircuit 
throUL'h  ir,in  irrindintr-pans.  a<ritators.  ami  spitz-lioxes.     The  ori"inal 


Kl.or  \TU>\     \T    llli;   CKxrii 


U.   MINK,    i;uiiKi;\    nil. I, 


12;; 


UlaillilMllnn    plMl.l,    l.Hlir   ,l(SI;r 1    1\„.  an    ;,rl,l   rirrllit.    Was   .Miuipi,,.,! 

onguiiilly  witli  wood  tliroufrlioiit  wli.iv  li,,,i„r  circulated,  and  with 
.lry-cnishn>j?  liMll-mills  for  ti,..  sanic  reason.  Later,  wet  crushing 
was  adopted,  hut  will,  a  frcsh-watcr  circuit,  kept  carcfullv  se{,arato 
In.m  tile  acid  circuit  in  uhicj,  Uw  a<'lual  separation  took  place.     The 

successful  .i<.v.lnpMient  of  the  flotation  pr s.s,  however,  has  enahled 

l"'th  cru.shinfr  and  .s,.paration  to  he  .'oinlucted  in  one  and  th,.  same 
eircuit,  and  has  thus  greatly  simplified  operations. 

I'll.'  liquor  that  was  circulated  through  the  .Minerals  Separation 
plant    was    apiuo.ximately    i>.-,,0()0    gallons  per    hour.     During    the 


F:n.  2:!.     thk  pia.nt  .\t  tiik  ikmiiai,  .mink. 

course  ot  operation,  therefore,  over  600,000.000  gal.— eipial  to  ncirly 
3  000,000  tons-has  passed  through  the  V2  iron  grinding-pans  of  "this 
plant  without  detrimental  effect.  \o  stronger  evidence  could  be 
produ.'cd  as  to  tiie  freedom  of  the  eireuit-li.iuor  from  acidity 
Ihe  maintenance  charges  on  these  iron  pans  are  no  heavier  than 
eorresi).,nding  charges  on  exactly  similar  grinding-pans  in  the  Icad- 
iill  crusher-section,  where  fresh  water  only  is  used. 

Following  e.xhaustive  e.xperiments  in  th,'  lal.orat<.rv,  various  media 
have  from  time  to  time  been  used  for  long  periods  on  the  commercial 
scale,  both  in  substitution   for  an.l   in  combination  with  oleic  a.'id 
Chiet   among  such   media   are   amyl   ah-ohol,    resin-oil.    camphor-oil' 
pme-oil,  and  eu.'alyptus,   with  all  of   which   ingredients  trood   work 

'■'^.' "   o'><'»"HHl.      Thus   Nature,    in   chi.se   j)roximitv   to   the   vast 

bodies  of  complex  ore,  has  j.rovided  the  means  for  tl,;  concentration 

or    Sllcli   nr^ia     fj\t^  +li,-.  ,.^ — ..4:..l    ,:i    ,i»   .1         *      _. 

,    ."    "  ' — -"-.i.-.i  t;::  tji  iur  .viistraiiaii  eucaiypius  is  one 

of  the  best-known  media  available  for  the  successful  exploitation  of 
•viractory  Australian  (,res.     It  is  of  interest  to  note  here  that  this 


V2i 


Tirr.    FI.oTATKiN    PH(((T>- 


'■''''''"■■'""'"  •"■  ""  -^I'MialKiM  pn.,|u,.t  ,„  ,1,,  t.TMluH.nt  m'  ronn.lrx 
'"■'■'  '^  ""■  '"•"■"""■  '"'  "  '•'-•"■'!  ""  tl)-  <  Vntn.i  mi,,,.  I,v  m,.  A„s,,-alia„ 
-HHalhorns,.  I|..„r,v  l.av..,s     a,„l  ,.   uas  als,.  i„  tl,..  „„ll,„i;  ph,„t  „„ 

""■  ^'.•""■''  '" """  '■'"■ai.vptns  ,„1  uas  li.st   „m „  .-i  ,•„„,„,.,■,.,., I 

siali'  lor  r()i]ii.|it,-;itii,ii  hy  t1c>tatio,i. 

This  satisfarl,„-y  sta-c  liaviiij;  I,,..,,  ,VMri,..,|,  atlr,,!,,,,,  ,.„„!.!  „„w 
';<■  ""•'"•'i  t"  in,i.rov,.„.,.nts  i„  .neth.Hls  .,f  ha„.lli„tr.  a,„i,  o„  s„.r.r,.stin„s 
"•'""  til.'  o«,„.,-s  of  th..  pat,.„ts,  it  was  f,„„„|  that,  hv  .■..,„„.,ti„ir  tl,.. 
';""""'"•■  '■'"■''  M'it/.-t-x  with  tl,..  I,.,tt..>.  ,.f  tl,..  „,.xt"  „.ix,.r  in  s...-i,.s 
that   all    tl,..  sp,tZ-l.„X(.S  ...M.hl   h,   k..pt    „„   ..„..   t\nnv.   tl„.s    i„,p,„vi.,.' 
the  sui,..rv,si,„,  .,f  th..  w.„-k.     Am  ..xp..ri,„,.„tal  ,,la„t  „f  this  „at„n. 
was  ,.n...t..,l  at  th,-  nul  .,f  ,„„•  X,,  2  ,i,„.  ,^,,,i„„  j,,  s,.pt..,„l„.r  ]|I10 
a.,.l   i.rov,,,.:  hi^^hly  s,m...s.sf„l.  tl,..  syst,.,,,  uas  alt..,-,..|  with  ...w,!!,!,.,,...; 
tn  this  ,„..tl,o.l  ,.f  wofkins.'.      Kxp..i.i..,i,-..  shows  that.   Un-  i,l..al  work 
th.'  1....1  material  shonl.l  all  pass  thr-ou-h  40-„„.sl,.  hiit  it  is  i,„possil,h: 

to  s,.,.m...   tl„s  ..o,„li,ltion   .,r  griii.lint,'  at   all    ti„„.s   i„    th,.   ,„ill    as 
a..s,^M,..,i.     .Mon.ov,.r.  altho,.trl,   th,.  Sitlphi,!,.  < '..rpor.atioM   was  .p.ite 
awar..    that    i,„prov(.,„..„is    i„    ..l.aracter   of   plant    a.,,1    „„.tlH„|s    of 
"Peratioi,    -.......-ally    w,.r..   ea.sily    possil.l...    th.ir   att,.„tio„.    hv    (,„,.,■ 

"t    M,v,i,r,,sta„,....s.    ha.l    to    1...    t,ir,„.,l    s,.,lulonsIv    to    i,„.r,.asiM,r    the 

P'-<"l<'<'t>oi>  with  tl,..  applian..,.s  at  han.i.  As  illu.st,-atii,ir  wl^rt  the 
"r,t,.r  n„.a,is  l,y  i,l,.al  ^'r'i.i.li.if:.  the  records  of  the  avvra -,.  ass-.ys 
of  r,.s,,]„..s  show  ,-onti.„.ally  that  wh.-re  the  av,.raK.'  in  y.im-  is  from 
-  to  _..)',.  that  portion  rftiiaiiiin^'  „„  4il-ii„..sh  will  a.s,sav  from  ;(  t.,  4^- 
y-inr.  As  ill.istrali.if:  th..  diara-.ter  of  f..,.,l.  an.l  provinfj  that  the 
pro..es,s  IS  t.ai)al,le  of  l,a„,llii,jf  sueeessfnlly  the  verv  finest  mat..rial 
slzlns.analy.s^^s  l,y  eommen-ial  screens  of  th..  f.,..]  to  the  j'ine-s..,.tioi, 
/ine-,.oneentrat..  as  shipp.^,!.  an.l  .le-I..a,iin-  ,,lant  l..a.l-..on,.,.„trat..' 
as  shipped,  arc  given  : 


Feed 

to 

zinc 

section. 

1        z 

inc 

■oncentrat 

c. 

ne-leadin^ 

lead 

Throimh 

On 

'r 

Throiiiili 

On 

-; 

Tlirough 

On 

'"r 

40 

4U 
60 

11.2 
21.4 

40 

40 
III) 

1.5 

40 

40 

60 

1.9 
7  5 

60 

80 

19.4 

•0 

SO 

21.1 

CO 

80 

15  8 

80 
130 

130 
180 

15.6 
7.3 

SO 
131^ 

130 
ISO 

21.7 
7.4 

SO 
130 

130 

ISO 

18.8 
S  5 

180 

— 

25.0 

ISO 

31.4 

ISO 

47.5 

RKsn.Ts  OiiT.MNEi..  For  .•oi„paris..n  with  the  work  of  the  old 
mill.^the^following  summary  of  results  achieved  hy  the  existing  plant 
v.-ill  lu-  (if  intrrcst.  li.is  iaj,le  summarizes  work  don."  on  a  commercial 
scale  in   th..   Central   mill  over  a  period   of  twelve   months,   ending 


H.nl   NTluN     M     |IIK    (I.NTKAl.    MINK,    HUoKlN     llll.l,  ]  iV, 

"-■'■'•inlM.rL'.s.  I'M-.  ,u„l  <Uuu,nstr.iWs  ,;„ulu.nvU  tUr  vast  i.nprov..- 
rn.'.it  u,  ,.o,„.,.„tra.H.„  ,,„„.,ir,.  „„.,|..  ,.„.smI,|,.  I,y  ,|,,  a,lo|,tir.M  ol 
llii'   niilalKMi   j)r s-s. 

S I  M  M  A  KV 

' A^av  value. ,       ^^  Hoiovcrifs.  -^ 

IToi-.,     Ak.        I'I,,       Zn,      Ak,        I'D.      Zn. 

Lfad  conocntrale  e.x  load  section.  .111.11  :!:!.i  ,;;  „  ,;  ;  44;  ..,\  ,.  ' 
Lead  (oiKeiitral..  ...X  (l.-had  plain    .    1.4      .^d,;,      ,;j  ,-,      j^.'-,        5,^      ''-]^        ,' ^ 

Total    lead   roticeiiliate.  .  . 
7Aiic   (oneeiitraie    


.17.4 
.32.7 


I«.l 


«i;.7 

v.l 


7.1 

4t;.4 


5IJ.6 
42.1 


78. 2 
15.9 


7.1 


S4.' 


Total    concentrates    5(1] 


92.7      94.1      91. S 

Mo,iiti,-atioi,.s  .,f  the  wet  n.ill  ar>   ,i<.u  i„  l,a,i,l  (uv  the  i.nprovetne.tt 
"t   the  trriti.lin-    hut  it  is  felt  that,  as  the  proporti,,,,  „f  l„wer-level 
or.,   merea.ses.   the  fr.-i.„lin^  appliat.ee.s  will  have  to   he   i.i.Teased   in 
or.ler  t,.  allow  for  the  ti„er  erystallizatio,.  „f  the  u.n.erals  in  the  ore 
«.s  t.irther  depth  i.s  attained.    The  writer  i.s  of  opinion  that  the  fipnres 
riuoted  clearly  .show  that  if  the  i.leal  f,M-indinfr  i.s  ohtained  the  already 
high  recoveries  of  metals  will  be  further  aii<r.n..nted. 

It  is  unicp.e  in  the  history  of  eoneentration  that  so  far-reaehinp 
an.l  extensive  a  .levelopnient  should  have  reaehe.l  its  pre.st^nt  state 
ot   perieetiou  m  so  short  a  space  of  time,  arul  more  wonderful  still 
that  It  should  prove  applicable  i,i  an   e(,ually  masterly   manner  to 
so  tuany  other  clas.ses  of  ore.     There  can  he  little  doubt  left  in  the 
......ds  of  those  who  have  seen  this  n.-w  system  of  concentration  that 

It  i.uist  ot  n..e,.ssity  .spread  to  all  parts  of  the  world. 


I 

t 


I 


iL't; 


TIIK    KI.UT\TIM\    I'liocESS 


WHAT  IS   FLOTATION? 

|{y  T.  A.  JiuKMiK 

l;lH.l.„n.  u,  ..s  lat.M  pl,as,..  .s  a  ,,n„.,.ss  „f  ..o.M.ntratm^  ores 
''>  ''--tliu.j?.  WlH.n  ..n..l„.,i  ,„..,  ,.,vv,„u.sly  „ux,..i  uuh  wat-r  a,.,! 
a  ivlat.vvly  nunute  ad,l.li,m  „f  „il,  is  aj,'itat..l  violently  i..  tl,. 
I.ns.„.c.  of  a,r,  a  froth  is  for,„,.,l.  Tl,is  frotl.,  risint?  f.  th.-  surfa,-. 
'"  '"•  l"l'";l  '"..MU.V,  ,s  la.k.,.  with  sulphides  or  otiu.r  nivtallu- 
|nirt.,.K..  uh.l.  th,.  ..arthy  .aat.riai,  or  «a„j„u.,  suhs,.!,.  to  th. 
'""torn.      Jh,.   troth  is  ••thi.k.  ,.„h..n.nt,   a,„l   ,,..rsist.„t  "• 

""■  '"nnaliou  nf  this  froth  ,lrp.M,]s  uj.om  a  .uin.h.r  of  phvsiral 
.•aws..s.  of  whi.i,  1,,.  huo.an.y  of  o,l  ,s  the  o,,.  „.ost  Kc-.u-rully 
a«.so...at...l  u.th  tin.  tlotation  process.  Surfu....  tension,  however  is 
the  phenomenon  to  lu^  .■ons„hre,l   lirst.     Then  vis-^osity 

Kvery   M.illnian    i,as    had   oeeasion    to    notire    how  "sulphides   are 
'•arne.l  on  the  snrfaee  of  wasi       •  ,er  in  a  stan,p-null;   for  ..xanmle 
wl.^M  water  IS  pa.vse.i  over  the  .,.,   surfaee  of  an  an.algan.atin-tahle 
or  a  vanner.helt.     The  n.etaili,.  partieles  are  dry  and  to  their  snrfaees 
IS*  attaehed  a  tihu  of  air  that  Inioys  tiiem  on  the  water.     To  a  .similar 
oause  ,s  due  the  lo.s,s  of  "Hoat  jrold'  in  tailin-      Most  of  us  learned 
'■arly  thiit  greaM,.  of  any  kind  was  had  for  amal^caMiation.     It  'siekens' 
*('■■  'i;.        suvcr,  e,..ntit.-  the  -loholes  ,«o  that   they  do  not,  eoalesce  hut 
ivinam    m   a   'floured'   or   nunutely   ^dohular  condition      Th„   ;ui. 
a.-ount  for  the  loss  of  ,,uieksilver.  hut  the  further  loss  „f  ^^old  nn.Jt 
'"•  '";i"'""l  '"  ""•  ''""t  "'at  the  tine  sealy  hri^^ht  .old  attaehes  it.self 
'•f."ldy   to   ti,e   oded  .spiieres  of  niereury   and   is  carried   with   them 
into  tile  creek. 

The  surface  of  any   ]i,,uid  behaves  as  if  it   had  a  film  or  elastic 
skin.     'IN,   tins   fact   is  due   the   variation    in   the   maximum   size   of 
.  rops  oi    .hflferent  li.|ui.I.s.     As  the  drop   cnlar^^-s.   the  stren^-th   of 
this  sk.n   is  exceeded:   then    the   drop    h.vaks   and    the   li,,ui,l    falls 
When  an  iron  rinp  is  dipped  into  a  solution  of  .soap,  it  will  1„.  seen 
on  taking  it  out,  that  a  film  of  the  liquid  .stn-tches  across  the  rin"' 
II    a  .small  loop  of  cotton,   ,,ieviously  moistened  with   the  .solution 
IS  placed  on  the   (il,„   left   „„  ii,e   rin-     fins  loop   can   he   made  to' 
a.ssuine.  and  retain,  any  form,  such  as  is  shown  at  .1  in  Fi-   24.     If, 

«That  is  the  de.s,.ri„tio.,  ^-iven  l,y  ,ho  Minerals  Separation  motalIu.-cis.« 
n,^,Vine ' ""  '"   "'""'''■  '""'"''  '"''■'"■  "'a '•'>■  "''»^^  "«i"B  '!>»■  Callow 


U  II  \T    l>    H.uj-  \|-|n.\ 


lL'7 


li"u,.\,.r.  ill.,  tilni  witliin  111..  Ic.p  is  l,n>kcii.  111..  Io„|,  iiiurH.,liat.l y 
;isMiii,,s  t|„.  .iiviihir  loriii.  shown  at  /; ;  .111. 1  iT  ii  is  now  ,|..f,,n.-("l 
in  Miiy  way.  on  hcini;  ivlrascd  il  spr'iii'.'s  hack  at  oner  f.  a  ciivl... 


Fio.  24. 

Th.'.sc  plicnoMi.iKi  indirale  tlial  the  parti.'l.'s  at  tli..  surfa.v  ..!'  a 
lii|uia   liavf  a   jiivat.T  r<.li,n-ncc   than   the   partiidis  in   Ww   interior 

nf  th.;    li.inid.     The    foruf   that,   .ioes   tliis   is  surl'; tmsion.      The 

oxperiment  with  the  rinj,'  and  the  h>op.  for  example,  is  ex{>lained 
liy  the  fact  that,  in  the  first  i)laee.  "th..  surfa.-e  tension  of  the 
liquid  aets  ecpially  on  both  sich'S  of  the  eotton,  luit  wien  the  film 
inside  the  loop  is  hroken,  the  snrfaee  ten.sion  only  a.'ts  on  one  .side, 
and  hence  draws  the  loop  out  into  a  eirele,"v 

Surfarc  t..nsion  ean  he  measured.  A  framework'  (Pig.  25)  eoiisist- 
A  C 


V-r.     1-         V 


^ini-..>uitl    ut    I-II.M. 


tA  Text-nook  of  Pli.vsics.'  ti.v  W,   Wat.^^oii.  iiage   19]. 

■■A  Tt'Xt  Book  of  ttie  Friiiciiiles  of  !'livsie<.'  by  Alfred  nanniell.  19]]. 


I 


THE    I-I.OTATIUX    l'li(;(;KSS 
in^,.fa,r.ns^,.,.s..  l,„-.l    /;.  .,,,,1   tu„  ^n,„v,.,|  slips  /'/>  an,l   I'   F 
/     /     >:   I.nsh,.,|    ,.,.„„.,    .,    y,   „„,    a    ,„,„„„,.   of   ,|„.    l,,„„i    ,s 

r  ;  ;  7'*''' ''7',  ,'''"■  ""''•'-■-^•-'-'•■•i-,hsa,„l„nni 

u     ///s  ,.„„,.,,  n.,,..iy;.     Ti„.  nunnnmu  ion.  ,.,.,, uin.,Mo 

i'-  .s  »,,..,.  w..,.l„  o,  ,.  ,,„„,     Tins  w,.i.l„  SUSP..,,.!,.,!  on  tlu. 

"1  '-■•I unls  tl„.  tens.on  of  th.  lil,.,  n„  ,1,,.  nuv.     If  the  fihn  stn.tHu.s 

;'•'•''  'I'':  ;-■•■///  -s  . I  /^  .iH.n  , In.  lilnM.s  an  area  r  /;rr-" 
"""'  "■'■'"'"  '"■"  i'*  'iistnlM,t,.,|  ov,.r  th,.  Invadth  r  /;  ■  ul„.n,v  iC  r 
■■•rn.s.nts   tl„.    suprrliriai    tension    arross    tli..    unit    of    l.ngth    r    A'. 

tiirn  1,11/  =---  r.r'  E  w  7'--  -  ";■', 

Tlu.s  the  fon-e  of  snrfao.  tension  l.etneen  u.ter  an,|  a,r  l,a.  i.een 
detennme,! :  U  ,s  ^  .,,..„.  per  linear  .neh  or  M  dynes*  per  eentin.efe 
ui.Hl,  iK.in,^  ,nte,.pn.,e,l  n.eans  that  40  ,M.nns  uouhl  he  supported 
hy  a  dim  one  foot  lonir.  ' 

The  surfaee  tension  of  various  liipihis  is  as  foli.iws: 

Tensinii  or  t^ni  ia<  «■  s  ■()■ 

,i     ,i,,  .■  •'tin     il,..liq„i,l  from 

Water    '",    '''  '"'■■  ^V.,,.,. 

l.(»0  a] 

J  J. 54  S40  A-io 

'^'^"'■-i    „.:;.  ^  *^^ 

Olivi.   oil 7  •  •  ■    ■ 

Tu,„.nti„..  ■;'  :l''!  -"^•= 

U.^S  -JQ    -  11-- 

IVtrol..ui,i    I, -f,  :^-^  ^l-^" 

Thes,.  ,u-e  jriven  .n  dynes  p,.-  eentnnetre  as  detennine.l  l,y  (^nin.ke, 
ami  n--..-.led  H,  the  ':..,.,/./.„/.,  ii,.,7.,uur..  Ifowever.  a  lupiid 
lias  another  eharaeterist,,  that  nu.st  no,  he  oveHooked,  nan.elv 
v.seos,ty  or  resis.anee  ,o  How.  This  ^>ves  tonjrhness  to  the  super.ie.al 
lilm  \\a,er-sjn,  ers  will  rnn  over  the  snrfaee  of  a  pool  like  hovs 
..   skates  over  thu,  lee.      The  spider's   feet   do   not    break   throufrh 

"'"""'f''  '■"'■''  ^'•^•"''  >""k<'S  a  dinipl ,  ,he  surfaee.     H.  U    Dii.,; 

^"■'"''Il.v  nuasore.!  ,he  pressure  ex.rted  hy  ,l,e  spider's  feet  on  the 
"ater_    He  photographed  the  shadow  of  the  din,pi,.  and  the,,  niounted 

o.H>  ot  the  sjHder  s  feet  on  a  deliea.e  halanee  and  mad,.  ,t  press  on 
t  '<■  "^.t<T  untd  >t  n.ade  a  dnnpl,.  of  ,he  san.e  d,.p,h  as  tha,  pn.vonsly 
oiiserved.  •' 

''''"•    ""^^    '»''"'^''    "''    ""•    ^i"'.i''''t    is    ilhistral.-.l    i,y    ,he    fan.iliar 

*Sep  also  patzp   11   of  tlii^  i,««v 


\\  11  \T    IS    1-I,()T\T|().\  .' 

fxpci'iiru'iit   with  ;i  yn'ii.MMi  iir,.,ll,..     If 


12:» 


villi  i)lacf  iiii  iiiviiiiai'v  rifriilo 
say,  a  lar,.  nirdle  suitable  lor  use  witl.  No.  .so  ,hn,„|.  ,„,  ,|,;.  ,„,,,•.,,,, 
'"   '^  i-^vl  of  water,   it  sir.ks  at  .,„ee  to  the  l.ottou,.  m  obedie.M-e  ,o 
1";  'au   ot  gravity.;-     If.  however,  you  pass  the  needle  through  vour 
liair,-  so  that  it  heeonies  givase.l,   it  uiU  float   on   thr   wat.-r       \Vliv 
the  ditierenee  of  behavior.'      In  its  ordinary  state  the  ne,..lle  has  "a 
';'"'"'   ■■;'■■  atta,h,.d   to   i,.      That    liin.,   l.ing   loosely   held,   is   ivadilv 
-lisi.la.ed   by  the   wat.  r.   so  that   the  nerdle   becomes  we.ted     that    is 
Hs  weight   eauses   it    to   break  through    the   elastie  skin   ,-o,i.stit,itin.^ 
the  suria.-,.  of  f|,„   wat.r.      ()„   ,ho  oth.r  hand,   when   th.   u.edle   is 
f?i-ase, I    th-  fihu  of  air  aronn.l  ,t  is  disj-lared  by  a  film  of  oil    whieh 
IS    hrmly   hehl.    because    lustrous    n.e.alli.    surfaees   havo   a    scLvtive 
adhesion    for  oil.     .^I.uvov.r,   gas-s  have  a  marked   adliesivne.s.   for 
">l^.  so  that  air  adheivs  readily  to  the  film  of  oil  „„  the  nee.lle      On 
ai-ount    ot    this  enveh.pe  of  oil  and  air,  the   nee.lle  is  not   w.ited 
that  IS.  It  tails  to  ruptt.re  the  surfaee.     The  needle  li.s  m  a  .iepres.sio„ 
H.   the  surtaee  of  the   water,   but   tlie  amount  of  displaeement   does 
'""/"•'•'■'■•il    for  th..  rtoati.ig.     Viseosity,  however,  mav  plav  a  part 
b.v  inerea.snig  the  tenacity  of  the  f.Uu.  the  particles  of  whii-h  are  so 
held  together,  or  cohere,  that  the  needle  fails  to  part  them.     In  short 
although  It   IS  eight  times  heavier  than  water,  the  .steel  floats 

Another  suggestive  experiment  is  that  of  the  grapes  in  soda-water 
1-d  a  gla.ss  two-thirds  full  with  soda-water  from  an  ordinarv  'svphon' 
;"nl  then  .Irop  two  or  three  small  grapes  into  it.  The  g'rapes  sink 
'■;  ""■  l"'tt<,m.  but  they  b,.eomc  restless  almost  immediately  and  soon 
nse  to  the  surface,  one  after  the  other.  Thev  ,io  not  remain  there- 
hrsi  one  and  then  the  other  sinks.  This  performance  will  continue 
'">•  I'alt  an  Hour,  the  individual  grapes  rising  and  falling,  not  alwavs 
Hi"  whole  wa.v.  but  maintaining  a  condition  of  intermittent  activ.i" 


I  liey  become  quiet  <mly  when  bubbles  cea.s,.  to  be  grwierated  at     1,. 
bottom,  that  is,  when  the  earbonie-acid  gas  has  been  driven   out  o 
t  "■  wat..r  by   the  relief  of  pr,.ssure.      Hy  wat.-hing,   it   is  sen   that 
II"'   'nibbles  attach   thems<.|ves  to  the  gra,.es  and  biiov  them   to  the 
Mirlace,  where  the  bubbles  break.     Sometimes  a  eouple\)f  grapes  wi 
••"ll'de  and   cans,,  the  adhering  Imbl.les  to  become  .letachcl    so  tir 
"•"■  ^"'  l">th  of  the  graiies  sink       In  the  end   the  bubbles  b,.come  f„„ 

!•!,!"  ''!!"^_'I'."  "'■"'*:""■  .^"  "''"  ""'  ''"''•••  <■'■«■  "my  part  of  tie.  way: 

Dui'iiiLr   the   earlv 


it 
too 


tiiiallv. 


iliey    lie   iiiotionl(.ss  at    th..   bottom 


iS..,-  „;^,,  |,|,.  .1.-7  aim  :;.,i;  „\  iliis  liooli. 
-Or  even  tliroiiKli  .vnnr  fiMi;ers. 


1.30 


TlIK    ri.oTATKlX    i'Kdfi:: 


•■"•I'vr  jK.rt   nl   ,h,.  ,„.,.fon,„nr,,  ,1,,.  t:r.|„.  will  .  ,ik,.  ti,..  snrfa-,.  „f 
'II.'  "airr  ami  vrU,uwl   ,■,,„„  ,,  as  if  it   uviv  a  innnhraiir 

I'-    I'uovan.-y   of   nil    is   ,|„.   ],|,vsi,.al    Tart    most   assonat.,]    wuh 

I'"  lirst  ,l,.v,.|opMu.nt  of  Ho.ation.  alth,  u^^li  il  is  .sul,onlinat.d  in  th. 
'''It.T  I'hnsrs  of  ,|„.  pnHvss.  .),]  has  a  sp..,,,!,.  .nuity  j.ss  ,l,a„  thai 
;'l   "al,.r.  an,l  tia.n.for,.  ris.s  to  ,1,.  surfa.-r  ^^hvn  niixni  with  uat.,- 

iH'  li-ht.T  oils  ranj:,.  i„  sp.riti,.  .,,uify  from  ().,s  to  ().!.-,.  as  a.'ainst 
'  '•■   1"  "I   wat.r,  so  that   th.  .nartrin    for  l.uoyinfr  parti-l.s  h.'^avi.'r 

tlia.i  wat.T  ,s  s.nall.     For  .nsta.Mv.  to  ,„ake  a  ,uixt,„v  of  y. M,lphi,l.> 

'"Hi  '"1  ns  l,.-ht  as  water,  it  u-o„l,l  l„.  „,...,.ssary,  .v.,,  with  th.  li-ht.r 
m  s.  to  us.  iron,  ;!  to  l,",  titnes  as  ,nuH,  ml  l,y  wrij^Iit  as  thr  l,h.,.,|. 
ilns  s„,.,..sts  that   flotalim.,  ev.n   as  .•on.lurt,.,!  on   tl,,.  li,„.s  of  the 
"I'li'i-   pat.'iiti'd   processes,   eaiinot   be 
of  oil. 


due    eiitiP'ly    to    th,.    Imoyaney 


IIh'    sele.tiv,.    a,lhesio„    of    oil    for    ,,artie|,.s    havi,,-    a    metallie 
ustre    ,.    a   ,le,.,sue    faetor   in    the   proeess.      It    has   hee„    said    that 
liis    adhesiveness   is    eliaraet-rist  ie    of   sulphides;    hilt    it    is   exhibited 
'v  tellnndes  and  hy  ^rraphite  also.     Sinularly.  it  has  hrm  impnl..] 
''\  '"""■••■•''    "'"i  to  •  metallie-^  partieles.  h„t  both  terms  „,mld  imdude 
substanecs  o,i,s„l,.  ,h,.  ran,.-  of  this  ,,heno,nenon.     Apparentlv  if  is 
'I-    '-''a  I--    lustre    tiiat    is    the    decisive    factor,    for    this  'would 
""•'";''■    '!';■    ""nerals    especially    anumable.    such    as    molvhdenite 
frraph,  e.  the  telh.rides.  and  the  bri.dit  sulphides.     The  etVc'-t  of  this 
•nnrked_pret..rence  of  oil  for  lustrous  metallic  surfaces  is  intensified 
I'y  tlie  tact  that  cases  ^sud,  as  air'^   have  a  sindlar  adhesiveness  for 
"II.   so   that,   li    present    in   water,   ihcy   will   .join   in    prcventin.-   the 
-•..n,^o,    the   metallic   surfaces.      It   is  an    e,,ually   important"  fact 
tlial    Muart/   ami  other  Raiifruo-minerals.   havini:   .,  'non-mctalli,.'   .s 
asrainst  a  -tm.tallic'  Ins.re.  exhibit  ll„.  opposite  prefcvnc  :  thev  ,re 
feebly  .adhesive  to  films  of  oil.   and   therefore   to  tho.<c  of  .,.    ,,,,i,, 
thoy  are  stron^rly  adlu'sive  to  wat.r.  that  is.  thcv  are  ,.,.,s,lv  wetted 
III-   ivasMn    lor  tins  ditrerence  is  not    known;   it    mav  brhne-  to  ll,o 
as  yet.   mysterious  realm  of  eledro-.statics,  hnt   it   is  a    fact    that    th.' 
<;nrvc  ot  ,.ontac,.  or  waibanf.de.  i,etwecn  metallic  part.cl.s  a.id  water 
IS  convex  while  that   between  earthy  partides  is  ,.oncave 
__JV]iat^.ver  the  rea.son  for  this  ditlVrencc.  if  ran  be  accentuated  by 

■■■Metallic.'    i„    this   ..ontc.xt   ma.v    mean    n.iMernIs    wi,l,    ;,    ,„.,,-,lli,.    I„.„v 

Hiln.m.   ,r,-,„!n.,.    an.l    ■mincrar   nK.v   .,e   n,can,    i„    „,,.   ..„.,.   of  on      ,    ,: 

aliu.l„c  part  of  „,.■  v..i„  or  ,o„,  ,  a.  .iistin.ui.h..,,  f.-om  „„.  wo,„,Icss  ,a,      v 

matter  or  l'.-ui^mic.     m  French,  ,„n„rni  means  'nr.  •     Sn ..,....,!      .^ 

«.thoul  metallic  I„s„,.  is  readil.v  amen;,hle  to  flotation,  nanclv    .-innah.  r 


Wll  \T    IS    IT.oTATIOX 


l:il 


.      l.n.  non   ,.,     Ik.   u.„.,..      -A,.,,,,,!,.,,    u.,,.,-  has  a   ..va,,.   u-..„in, 
-  .huH  ,,,.„„.al  wa,,....-'     K,„.  „,;,  ,,„,  ,,„.  „„  .^sla.ton-  .xpl.: 

.l..ss.,l  e  any  .oa.n.,.  of  „xul,.  on  ,h,.  ,„„„„i,,  ,,,,.„,^,   ,.^,,  ,,.,      , 

:;;:'■" '"^^^""^'  "''''•■"■'" ''n.Muuul.  t..  a..di.y  o,- tl,,.  ..,.:  Lv 

.n,     .  a  .orrosue  prnrt  ration  l„.n,.atl,  tl,..  surfaee  of  th,.  ^.an.M,.      ' 
ilH'  .•.,l,imou  of  ari,|  in  ,|na,„i(y  ,>ro,lu,...s  anotl,,-,-  ertVrt    nai„..lv 

"f'     "''^•'"'      H,odo,.l,n,site.     or    other     ..arbonat.s     su.h     as    are 

prcsM.u,  ,t  ,,s  po.s,l,lo  to  n.h-a.so  the  air  in  the  form  of  I,uhl,|,.s  that 
attach  the,nselve.s  to  the  „>etallie  partieh-s.  Uke  th.  hla,i,h.rs  use.,  hv 
persons  U.„„n,  to  swin..     Mo, ver.  hy  a  violent   a.,tat.on  of  t  , 

nta,  ^le  a  har^e  volun.e  of  air,  which  will  rise  (hn.n.h  th.  ,„a.s 
■"  tlH^  -rm  ot  niyna.l  hnbhles.  crmstitutinjr  a  foan,  or  froti,  ..f 
varyinsj  stron<.';ii  an.!   persistence. 

"il  rcluees  the  surface  tension  of  water,  that  is.  hetv  .vn  water 
.  H    -n     I  „re  water  has  ,reat  surface  .ensinn.  it  also  has  no  super- 

1^1:T'\''''^'''  '''''''''-  '■'•""'■  The  addhion  ot' oil 
lo^^ers  the  surtaee  tension  and  in.parts  a  decide,!  viseositv  to  the 
M,rf^.ce  of  the  water.  That  is  why  th.  pourin.  of  oil  on  troul  d 
^Mte.s_  abates  ,i,e,r  turbulence.  That  al.so  explains  whv  the  placin.^ 
0  0,1  u,  stagnant  pools  kills  the  larv.  of  the  ,„osquito,  which  the,'; 
hnds  ,t  ,u^,.,sMhle  to  a.ihen.  to  the  surface  i,y  their  l.vathin.-tuhes 

(S(.,.    i<  ]ur,  26.) 


Fii: 


'  M»  AK   ,„.     lllK    M„s,;llTO   .VTr.^ClIKM    TO   SIUIV. 


K    01      WMI  It. 


r.i-2 


TUK    FLOTATION-    I'liOCt-SS 


.        *'""  ;■     '     ■■    l-''Nt,r,.|    ,snM,,-l,ul,l,l,,       Tl„.    oil    nf    tl„.    s„.n    is    -u, 

::;';;"■■''.;  "'^'.' ;'77  "-"•■•■' —,.„,,„•„„...„..,.  „vs,,,,.„: 

'"    -Pnn.y,  ,„akn.,  „„.  m.n  stro,,,.-  and  I.ss  p.-one  to  ..ollap.so  < 
'Ins,.   -n,l..rs,l,,.  ,,u,,i,|,,  ,,,,,,,,,,,,,, i,,,,,,,      Th,.  huhhl..  .In^vfo  e  is 

;■■<;''--  lHs.n.u,n   .,■  sn,.ra,..   ,.,s,on,    .n..   , Ms  an  ..h.,i,.   si  ; 
^-''■■-  <;"H'-n.  .as.  l,k,.  a  i.aiioon.     H,.,v  also  .he  p.-op.Hv  of  vis.osif 

;     .;  pnsunMo  ,h,.  au^  as  in  a.hanon.  .n-,.s  t™nM,Mh.  su^ 

'•"■  .  .""■  ';-•""■•"-„  of  low  tension  an,l  l.i.h  vis<...si.v  ...ahh-s 

'■'''!'.  ns.n.  ,    n>u,h  ,he  li,„i.,.  to  envelop  itself  i„  ,„o  surfaoe  fihn 

"'    ""■     "l.n.l     wl„-.h    th..    tension    of   ,he    l.„bble-,ihn    is    not   stn... 

enough  ,o    „.eak^  .,  nurt  the  l,„.,Me  endures.    Tl,e  nois..  n.ade        ,   ^ 

''""'"-, "    r   ""'•'''•  «"^'^'-'^  t'-^  fa-t  tlKit  it  is  a  reeep.a.de  of  ene'.-.v  * 

I  . J|uhl,le  .s  spl..n,.aM,eeanse  ,ln.  spin.n.  is  tlH.  slu.pe  involnn. 

1  es    snrlaee  o,-  snp..,.,ieial  area.     Ti.  I,n,,l,l..  has  an  a.tinhv 

'      '1-   Ins.nH.s   „„,all,e   partieh.  and   adheres  to   ihem.   as  it   also 

.dh,.n.s    o    hes-noo.hsidesofa.lass.     This  par,  vie  of  air.  „r  ,„her 

'  ^^1"  I'    t  has  been  .vnerated  and  the  n.e.allie  partieles  do  no,  1,  eak- 
n.nd,  .hjd  sl<,n  f,,r  ,,,,■  san.e  reason  as  ,he  greased  need),,  fade, 
'"'  ill-owned  in  tli(>  water. 

,„/'"'"■  "';.""""  "[  "'"'''"  "''^  "■^■^'^'■^  ""■   '■"•••""'i'^"  ^'f  t'uhhles   in 
I     nass  otore  and  wa„.r.     Ti,ese  three  eonstitn,.nts  of  the  Hotation 
-'(    ^.-e  nuxed   udnnately  so  as  to  f.nn  an  Vnnd.sion.-  .sneh  as  ,s 
P  .H.i  In-  .Mayonnaise.     The  air  present  while  ,he  ,.n„d.sion  is  l,ein. 
■I'i"  H.rn.shes  the  pras  tor  the  hubhies.     In  order  that  thev  n.av  lif^ 
""■    ';";'^''I"'    P'-t.eles.    they    must    endure    lontr    enough    to    permit 
-n|Pl''t-.'|..ra.,on  ,,f  the  .netalUe  part.-les  fron.  the  earthy  partieles 
.  t  .s.  the  sort.njr  ot  the  valuable  fron,  the  non-valuable  ..on.pon.nts 
•'    <lH'  '"v.     I-"r  the  purpose  of  metallurfzieal  eoneentration  the  rate 
'"  "■";■''   ''';■  ''"'''''"^  '"•>•«♦  '""^t  be  slower  than  that   at  whi,-l,  thev 
a-  I.-.nfr   lonned.     An   etl'eetive   froth   repivsent.s   a   n,ultiplieitv  of 
I><'.-s.s,ent  bubbles.     The  .vlative  .stability  of  the  bul.bles  depends'also 
"'7;  ""■  '^""'  "I"  '"1  'Mnploye.l,     P.ne-oil  n,akes  a  brittle  nhn  :  ereosote 
yields  an  elastic  enveloi)e. 

I'..v  a  wonderful  correlation  of  physi.-a!    forces,  the  metallic  p,,.. 
nH,^co,„e  attached  to  the  bubble.  n,a.le  in  the  u.etallurgical  cu.ul- 

<C.   V.    Ho.NS,    Soai)    liiilililes.'   M.-iire    103. 
'■Daiiliiell,  Op.  rit..  |iai;e  27S. 
♦See  also  page  nil  of  tliis  book. 


WHAT    IS    ri,(iT\Tl().\  ? 


|:i:{ 


s.nn..usu,.hau.n   ■-  to  mtv,-  .s  .  proUvtiv,.  .n,,,.,,  ,|„.  „„,,  „.|,..  ol' 
v.rv,,.^'   ,s,ze    in,.rl,M.ki„j,   „„    its   .sj.ln.n.al    ..nvlop,..      Th..    l,„l,M..s 
;"""-t   ........ral   are  J.k.  a   ball,,,.,,   with   a  w,.ak   p,s-l,air,   uhid,   is 

lik,'ly  t„  l„.,st.  wl,il..  ,|„.  a,-„.,..v,l  l,„hl,l,..s  a,v  like  a  hai;..,.„  «,tl,  ., 
Mnm^  iras-l,air.   whi,.h   .l,„s  „„t   l„.,.st.      Va,..,y   „(  .ix.   a,„„„^  tl„. 
""•'"""■  '•"'■'"■''■^  •■^'^•'"•^  "»'  '•""st,-,.,-ti„„  „f  tl„.  i„t..,.l,„.ki„ir  ,„i„..,,,| 
'•""•  ""  '!"■  I'ul.M,..  just   as  ,„at..,-,als  „f  vari„„s  si.,.  |,..|p  t..  n,ako  a 
,l,.|is..  .■,„i,.r,.to.     \lnu-v  sjii,,,.  ,s  ,i„  lii,„],-a„cf. 

r„ti„,at..  ,„ixi„<r  is  ,v,|ui,v,l.     Tl„.  ,„.„■,.  tl,,.,,,,,^!,  the  „,ixi„u    ,l,o 
'•l-'n.c-  tl„.  s,.pa,-ati,.„  „f  th..  „H.tall,.  In.,,,  |h,.  eai'thv  pa.'ti.k.s     Thje 
IS  sa,.l  t„  I...  ,i,„.  t..  th..  ,-.„„pl,.t,.  ,.ili„fr  „r  ti„.  „„.taili,.  parti,.],.s    hut 
It  ,s  a  )a,t  that  no  „il  ,.a„  1„.  .lis,,.,-,,,.,!  o„  tho  ,„„,.,.„trato  wi,..,,  us,,,- 
""■    '    ^"    '    I'""""'   "•'   "'I    I"''-   t,u,   si,fti,.i,.„t    i„    ,„„st   ,.as,s    for   th.' 
pur-jx.s,.  ,.t   th..  pr„....ss.     The  ,„ixi„ir  ,„ay  he  l.eneH.-iai   f.„-  m,s..„s 

"tli'T  tluu,  th..  ..,li„j.  of  the  .•..„..e„t,atal.le  parts  of  th,.  or,- ■  it  ,.,av 

'■Hus,.  ,.,„.u.h  tn,.ti„„  to  .-h.a,,  tl,..  „,..tani.-  surface:  it  ,„av  pn.,„ot".. 
su,.h  a  s..„t.o„  of  ,i,e  oil  i„  the  water  as  .n.sur...,  the  fo,',„atio„  of 
th,.  rifflit  ki„d  of  hi,l.l,],.s  for  a  „)iii,.ral-,-arrvinfr  froth  Il.at  I.y  th,. 
uuectK.,,  ,.f  st,.a,„.  i„er,.as,.s  th,.  ,„is,.ihility.  ,.r  ahiliiv  (,■,  i„.  ..iix,.,! 

"t  the  oil.  th„„„„cr  it  .so  that  it  will  ...xteu.l  ov,.r  a  la, r  surfr-e    ..s 

'-'"-•r  ,s  wa,-„„.,l  to  „,ak,.  it  spr,.a,l  over  pop-.-or,,.  .Ma„v  ..„,„„„',„ 
"lis.  .s„,.h  as  -.-...l  oil-  a„.l  ..th.r  for,„s  of  olri,-  a,-i.i.  a,.,  s.'.li.l  a.  tl,e 
<"-<l,i.ary  t,.„,,.,.,-al,„.,..  so  tliat  l,..at  s„ffi,.i,.„t  to  ,.ai.s,.  the  t..,-.,.e,-atu,-e 
•  It  the  ei,iu]siti,..l  pulp  to  a1...ut  SO"  F.  is  .h'sii^ahle. 

To    a[.ply    this   pr..e..s.s  .,f   ,.,.„,.,.„ti.atio„.    th..    ..iv    is   erush.vl    to 
the  de,ir,-e,.  of  fir.„„ess  ,.,.,|,„r..,i  to  s,.pa,-at..  tl„.  ,„..tallie  „,i„erals  fro.n 
tl...  earthy  f.a„^r,„,     Ti,is  ,„ay  „,..a„  auythiujr  fi-,.„i  40  t,.  2n()-,„e.sl, 
Jhe  crushed  ore  is  tl„.„  mixed  with  wat,.r  i„  th,.  ratio    sav    of  'M 
.'ilthouirh    ti,..,„vtieally   2:1    woul,|    ,„.,k,.    a   l„.tt..r   e.uulsio,.     oil' i.s 
•"l'l..,l.    .,;,y.    ,„    the   proportion    of    k    Ih.    per   to,,    of  or.  ■    a,„i    the 
>mx(u,.e    IS   atr,tate,l    viol,.„tly    i„    th.    p,.,.s,.„..e    ,.f    ,-;ir,    ,,v    p;,d.lh..s 
'"■   lH.i.te,-s.   I.y   ,,as.satr..   tiirous..),   a  .•.■nt,-ifujral   pu,np.  or   hv    jets  of 
eoiupressed  air.     A.i,!  is  „ot  „..,.,.s.s.„y.  as  w,.  „ow  k„ow,-\"al'thou.^h 
It  has  h,.retof,.r,.  1,...,,  ..ousi,!.,,.,!  .....piisit,..     \V;„th,.r  oil  is  al.s,.lute]v 
ess..Mtial  ,s  ep,.„  to  ,1,  aht.     A<ritatio„  of  th,.  ,,ulp  i„  the  pr..sei„.e  of 
air  .s  the  p,-„,„.  fa-tor  i„  p,-,,,!,,,-!,,..  il„.  d..s,de,atu,u.  „aT„..lv  froth 
AMiat   „,a.-li„,..s   a,-,.    h,..sf    a,h,pted    to   ..„s„re   p,op,.r   afrita<m„    is    a 
inatteMor  s,.i.arat..  eonsid..,.ati,..,.     .\e,-atio„  ,.f  a  li,,,,!,]  I.y  af,ntation 

•■  Flotation  „i  a  Alo.xican  Mill,'  Mi,n„p  and  SeicUifi,-  Prrss  Julv  04  19,5 
paue  r::i  Also  Cha.les  Buttefs,  .V.  .(■  S.  P..  Aup:m  21.  191,5  See  ,"as..s  -»■?' 
.■nifl  iL'i.  of  thi.s  t.ook.  ' 


134 


THE    ri.OT.VTIoN    I'li.K'FSS 


i:;;::^.;i:»;::,;':;;:i::;:::L:;;:;:;;;;:j:'-;,::^ 

"    ""■  'I'niH.st,.  operations  of  ,1,,  l„,„in<.  of  , s  ■,o,l  ^ 


WIfV    I-    I-MITMKIV  " 


]:i5 


WHY  IS  FLOTATION? 

By  Cinui.Ks  T.  I)i  iu;i.i. 
(From  the  Muiin:,  and  Sviniliriv  /',«»■  of  September  IS,  19]:,) 
So.,,,.  „r  tl,t.  lu,„la.„..utal  pnHripL.s  „f  tl.is  ......c.c.ntrali.,,,  -..psi,],. 

.low..,     as  it  ...ay  he  t.r.,...,l,   lu.i.,^.  .si.ri,  a  „ew   ..u'tliod,  l.avo  been 
<)verl,.oki..l.     TlK^.re  has  h,,...  surh  a  .,.a,l  scra.i.M,.  to  get  results  in 

adva.iee  of  tl.e  -other  iVlh.w,'  j,,,!  ,„  p„„.tral I,,,,,!  of  seereev 

ctoreed  hy  patent  liti-ali„n.  that  there  has  been  1.         ii.„e  t.,  answe'r 
the  question  as  to  why   the  heavier  mineral  tl„ats  aii.l   the   lighter 
f,'an<rue   si.iks.      Jn   this   hn/./iwr   ..hiu,!   of   se,'reev    the   stud.-nt""  ean 
.hstni-uish  sueh  phrases  as  MVoth   tlotation.'  'surface  tension  '  'oil- 
hlms,'    'l),.]}avay    Hoat.'    -ii-iuid    skins,'   ete..    all   of   whieh    tend    to 
eonfuse^  rather  thu.i  answer  the   main  (piestion.     A   IVw  articles  in 
the    ma-azines    haw    given    various    data,    pl.enom..na,    eaus..s    and 
effects,  but  no  definite  theory  explaining  these  has  been  elearlv  stated. 
The  action  of  any  flotation  machine  i.i  successful  operati.ui  seems 
quite  simple,  the  mineral  floating  in  preference  to  the  gangue   giving 
rise   to   tl.e   plirase   's^deetive   flotation.'     All   that   is  necessai'v    for 
the  one  type  of  machines  is  to  place  tl.e  mineral  particdes  gentl.\ 
on  the  .surface  of  a  li.|uid  s,.  that  they  will  not  .sink  or,  in  tl.e"otl.er 
type  of  machines,   attach    to   them   something  of   a   lighter  sperdHc 
gravity  than  the  liquid  so  that  they  will  rise  bodily  to  the  .surfaee 
On  the   face  of  it,   this  is  quite  .simple.     Apparently  tl.e   simpl.>.st 
ol  all  IS  to  attach  'life-pivservcrs'  or  .soi.iething  buoyant  to  the  mineral 
particles. 

Herodotus  .h'scribes  how  ■'the  virgins  drew  up  gohl  bv  n.,  aiis 
of  feathers  daubed  in  pitch."  Therefore  this  or  an  oil,  for  in.stance 
can  be  employe.l  to  float  mineral.  The  Elmore  patents  for  this 
flotation,  due  to  the  buoyant  property  of  oil,  are  still  in  effect.  Owing 
to  the  large  quantity  of  oil  necessary,  as  well  as  other  things  that 
make  this  method  of  no  commercial  value  at  present,  th-  only  'why' 
to  be  considered  in  this  class  of  flotation  is  the  si'lective  action,  which 
will  be  (liscu.s.scil  later. 

The  simplest  a.,,1  ch<■ap,^st  'life-preserver'  is  undoubted] v  the 
pneumatic  one,  which  is  beyond  the  time  of  Herodotus  or  perhaps 
even  history  it.self,  since  eggs  and  .ream  were  surel\-  f.-,.tl.ed  before 
the  stylus  was  khuwr,.  Aii.v  liirie  gi,-I  who  has  helped  her  mother 
ni  the  kitchen  can  tell  how  any  foreign  substance,  sueh  as  a  jiiece  of 
egg-.shell  for  instance,  is  buoyed  up  and  brought  to  fl.e  surface  bv 


136 


til 


IHK    KI.dTATKl.V    |'i{,i(i:ss 


''"■'"'  imim,i,.s,    'n,,.s,.  .,,.,.  I  ,,i  1 1 

•-•-!.>■    u.nnua,     n.;  ''7''  ;'''■■'''■''  "''^''  '■'-'''• ■-,..•.• 

is    --plv    ;,,,,.,,    ,r    ,,i,  ,        '^  '''''•:'^"   '"'-'■"'•'"■"    ■'"-"I".    IHM    , his 

u.s,,..     ■  '-'"'^  ''   •'.v-pr.uiu,..   tl.„    u-„ul,I  ,„|„.ru,s,.   ,.,  ,„ 

.■-'•":■*■'■:-.;"  >■ .'■'•^ 

.•iou,i  „r  s,..., V   ,.„„  ''■'"""■  ""^^-  -"•••"">',i..,i  i,v  ,, 


nr.    nr   attacliinjr   .-, 


if    liiiiihlcs    t,,    niiii.Tal 


-  ■M.Hw  1 ;';;.:'.  :''''7''' ''-- •''.'.>'''■■  ...  n.. 

'.^.'inn,  ulMl,.  in, !,..,.■    ;.'.''''•'''■':■  '^''-'   '■-"--. n- 

w:lll,..  ,,,!<,.„  up  la,,.,-  '.VI-  <"   ...-Inn,,  is  „s,.,l.     TIh-s.. 

TI.Mvlnn^,!,,.  ,w,,  prim..   ,...., ,nsit,.s,,,rt,,,,,i.,,,,,.. 
'■     -\tta,.innent   „l    l,ul.l,l,..s  to  solids- 

...Mt;,;;::;:;:;;:;:;  •:;;::;-• '■''-''--■•^^ 

---'- -i^.r:;;"..:;;,;-^:- :';::;■ :';:;' ■  '^-  -"  ""• 

-•  ''um!;;::';i;:  '::::r;:: ;;, '";■  "-^--■^  -•  t...  iish..s  ,„a„e 

'•'-  v,.a,-s  a.„    kn  w      u  m     "   "     ""■  "'   '""   """■'•  "'"'   ^-^   --   a 
■'•'-■•■    was    ,,i.!..I       J'     ■■''"'■'•  '■"'!'-'''''-'^-'-''-'''''I-  in  uat..,.. 

' n   Mown   in,.,  ,h,.  „-„,.',.  '"'  '"    """    "I.'''''    '.<'v.> 

'■'■'.  'i-^i..     V'-i  L-      n    i         •';      "■  "".'"'■^^■'''"  "•■•'.V  -stain  ,1,..  li.V 

...  this  uav.     ,."..:,/""  '^       ■';■'■   '""■•"""''"'   '"^^  '^  '--"i.! 
'•.•-y..'n'r,,,.,.;;;,^  V;;.t^^^^^^^  Ava„a.,l,.  air 

"hrn  proM  ,s  .lissolv,.,;.     ()nly  nas..,.„,  LJ^  ,:.;,,  "l,;",;,'  ";'';''■      • 

^as  ,,iM  hf.  a„a,.lie(l  ,,,  mineral 


WIIV   Is  fi.otatiun  ',' 


i:i; 


t       H„„,  ,„„^^,^       '''-'a,.,  is,,ui,.kly.i..,„ons,ra„.,ll,vu„n,. 

r;  r    •"■'  "'  -•.  ""•>  ""■  '"'t'-n  of  a  ria.sk.  ,ill..,l  „.„li  u...,..,. 

.  riou   o     tiM.n-  own  a,.,-.,nl.  .vfuso  „.  atta,!,   ,l,;.,ns..lv,.s  or  1„. 

;'";"'•''   '"   ."'"   ■^'"""    '""'•''<-  '"■  ••".•.'      To    pn.v,.   that   ,1,....   sanu. 
-•'''I'- P-;t-l:'.  .  an  1,,.  H.a,,.W  l,v  ,H,1,|,,,..  ,,r  air.  i,  ,s  onlv  nX"^^^^^ 
•'•  '-;:-  ,I,e  M  and  pla,.e  ,1.  riask  on  a  hnt  pla...  w,u.n 
--■'I-.,  y  .-olh.t  an.  ,lr,v..n  on,  of  solnt.on   L  ,„..  ,..,,,   ,„;,      '' 

I    -IH.  sur  ace.     Son.,  on,.  „,ay  lu..  renuu.kMlna  ,1,,.  ns..  o,'  t..nu.^^^^ 

•  -   ;>^    ^IH'   solnnon    ,.ansc..s    ..nonKl,    expan.sion    o(    ,1„.    air    hn  ,1     s 

•  on..   .anu,nn..Uh   ,,.   ,a.or„,.„.,.   .niknltlns^^ 

—    on    no„n,^   ,1.,.    .nvally    u„T..as,.,l    si...   of    ,!,..    I,nl,l,|,.s       Whv 

'!'■''•'-''•"'-■ '-'.1.1.S  I.  a.taelnMl  ,o  „,in,.rai  p.Mlu.l,.s  in  tl..     1     ; 
ot  na.sc.nt  (.r  ili.ss<,lv..,|  air.'  ' 

All   ,M...a,    fac.,.s.    wh.n   thoron^Wily    nn.lrrstood,   an-   .icnionstrahl.. 
y  snnple  oxp..n„u.n,s  ui.h  n.a,..nal  a,   hand.     .Sonu-tinn-s  wh,., 
own.  n,an  a.  t   ■.  soda  fonntain  al.sent-nun.i.-dly  fo.-.Hs  ,o  s.i,-    ■ 
..^    P  osphat.  an,l  s,.,s  h.-fore  you   tl.e  straws.  <le.nonstrate"  the 
<'l"-  '-■    to  yonr  sat.sfaHnu,  whil..  ,ho  na.s.ent  hnbhies  of  TO    forn 
and   rise  ,o  tl,e  snrfa.e  of  th.   li,,nid,      Cn.sh   the  straw  siiH  , 
r.,n.,Mn.s.esothatonlyannn.nnn.ofaircan.,,-fo.^ 
\\,th   th,s  straw    Idow  a>r  ,„to  th.  eolorod  syrup  in  the  hot.on,  of 
the  ^lass  so  as  to   form  a   few  sn.all   ],n.,hh.s  that   eau   he  wat,.,.. 
;  .-ly.     These  hnhhh.s  that  eon.e  to  the  .snrfaee  are  eolored.       Vi 

■-.-;•  't-»  -•""  "^'"'■"'-  '^■'"^'•••'■•"•"-  ^'"-  *'-  o"Iv  part  of  he 
l.-l"-;l  that  ,s  eolored.  i.s  in  ,he  ,,otto„,  of  the  <,h..s.s,  th;  L  „u  t  e 
onveh.ped    .„    the   same   identical   portion    of   li.p.id    thr    H  i 

pass...e  from  the  hotton,  to  the  ,op  of  the  .hJ,-     I„  otl.:    w  rd 
the  an-    „.bh,e    on  being  introduced  into  ti,,.  ,,„,!,,.  ,  uZ^^'w 
urrounded   and  u.elosed   by  a   fih„  of   H.uid,   Ihich    ren.ai 
that  a.r  bubble  tiiroughont   its  pa.s.saee   just  as  if  it   were  •.  Zrl     I 
t  M..bble.     Here  is  a  concrete  e.an.ph^  of  surjlc^  tlml.       "    r^ 
that    an  be  measured,  as  explained  in  any  text-book  of  phvsies 

Tins  pheuonienon  is  worthy  of  investigation.     The  bubble   ri,s<. 
to  tlu.  surface  of  the  bquid  by  rea.sou  of  the  force  of  a.avitv      Tin 
js    the  force  of  gravity  is  greater  than  adhesion  of  the  n^oLmles  o 
the    air   tor   the   mnWnlno   of   ihr-   ];.--;.!        .!         ._       ■ 
mnahijn    the    liquid.      The    molecul^^'of  ihrnl^id  "mr  Ji;^y 
•See  also  p.i-es  .^IC  and  ,r-,7  of  this  hook. 


l:{s 


TIIK    FLOTVTIIIN    I'KOCKSS 


iiHK.Ilf:   tll..|„.srlv,.s  ilc.-nnllMj,'   to    tli,.   ,|,.(ililtiu,i   .,f   a   :.,||,i,j.       |„    ,,,|„.,. 
M.>r.]s,  the  fonv  «(  volwaum  of  any  sin^'l,.  niolwiile  witlmi  Ihr  li,|iii,i 

IS    .MilDilix,.,!    |,y    ,|„.    ,.oli,..siv..    fom.    ,.f    otlicr    .ll()l..culr,s    of    th..    liquid. 

An  .■xtran.'ous  fono  woul.l  !,.■  miuircl  to  s,'i)arat.'  tlinn.  An  air 
I'lil.lilc,  for  install....  iiitro,|u,-,.,i  info  ih,.  |i,,i,i,|.  unhalai,r,..s  this 
'■-li-siv  fn,.,.,..  It  is  s.-lf...vi,l,.nt  that  this  foiv,.  of  a  nmh.nih.  must 
.•ft  .■.|iiallv  III  all  directions  from  that  mohriil,..  Th.T.for..  iii..h.<Mil.s 
"'  ""■  '"I"'"'  "'l.i"'-''"t  to  Ih.-  air  l,nl,l,|,.  hax,-  th.-ir  for.-,.  .,f  ..ohesioii 
"II  the  one  si.ie  satisti...!  hy  tiiat  ..I  a.ija.ent  m.,l,.,.ul..s  of  the  li<|ui,l  • 
uhii...  ,m  th..  .si.h.  ..f  th..  air  Iml.hh.,  ther..  ar..  n.i  mol,...nh.s  .,f  th.' 
Ii.im.l  t..  ,.,,nali/,.  tliis  for,.,..  U.-inj;  .stati,.al.  this  for,.,-  must  l„. 
...|uali/....i  hy  that  of  a,l,ia,...nt  lii<..  ni..h...uh.s  in  a  traiiswrs..  ,li|.,.,.ti,)n. 
Sih,...  a  for,.,.  ,,f  ,.,,h..si.,n  uas  alr..a.ly  in  ..xist..n..e  hetw.'.-n  these 
a,l.iae..|it  m.,leeules  thi.s  for..,,  is  th  y  muiti|.li..,i  s.>  that  there  tli..ii 
.•M.as  a  -|.,.aler  ,.,.h,.siv,.  for.-..  h,.tu>..n  tli,.  m.,h...uh.s  imm,..liat..l v 
surn,un.lin..r  th..  air  huhhh.  than  that  ...xistiii-  iM.tween  th,.  m,.i....ul,.'s 
in  til..  intcri.)r  of  th..  Ii,|ui,i.  This  for,.,,  is  'surface  tensiim;'  it  is 
S.I  frr..at  that  th...s..  m,.h.,.ul..s  .if  th..  ji.iui,!  surrouii.lin<:  the  airhiihlj.. 
aiv   lirnily  h..i,l  t,.tr,.tii,.r  an. I  t.^rn  hu.se  from   a.i,ia..eiit   moleeul,>s  .,f 

the  li.iui.l  as  th..  buhhle  rises  to  tiie  surfi Tliat  is  to  say  siirfat'e 

I,.nsi.in  .-aiis.s  th,.  moh..-ul,s  .,f  the  li,|ui.l  to  f.irm  a  film  ar..un,l  tlie 
huhhl,.  aii,l  remain  with  it  t,i  the  exelusion  of  like  m,.l._...ul..s  during 
til.,  tim..  the  huhhi.'  remains  in  the  li.iui.l.  T.)  all  int..|its  an.l  j.iir- 
P..-..S.  this  film  is  s..,.n  t,.  h..  th..  same  as  if  it  w,.re  a  memhran..  ,.f 
som..  .s,.Ji,i.  Til,,  air  in  tii,.s,.  buhbl,.s  ean  no  m.ire  e.mie  in  ....ntaet 
"ith  the  li.iui.l  tiirouf.'h  which  it  is  pas.sinp  than  it  ,.,)ul,l  were  it 
inside  a  t.,y  liall.i.m.  for  instance.  The  buhlile  may  be  sai.l  t.)  be 
.•n..|.,.s..d  in  a  'li.iui.l  skin."  Th..r..f,)re  t.)  atta..h  this  bubble  t.i  anv 
.sulistaii..e,  this  li(|iiid  .skin  must  first  be  peiu.trate.l  .,r  bnikeii.  As 
S(.(.ii  fr,)iii  above,  tiiis  r..quires  some  force. 

As  shown  abov,..  th..  force  of  chemical  affinity  is  not  siifti,.ient 
to  over...mie  this  surfa...'  t..nsioii.  S.i  then,  it  could  hardly  be  expected 
that  a  m,.re  adhesive  force  wouhl  be  fjreater  than  this  surface  tension. 
Th,.ivf,,r,.,  t,)  atta..h  f,'as  1.)  soli. Is  in  a  li(|ui.l,  it  is  first  ncces.sary  to 
dissolve  the  gas  in  the  liqui.l  ami  th..n  e.\j)el  it  in  a  nascent  stat(\ 

'A  striking  oxperiPifnt  to  show  tticse  liciuid  films  is  as  follows-  To  a 
lieaker  partl.v  filled  with  a  colorless  oil,  add  a  small  (liiantity  of  permanRanate 
solution.  Blow  air  throuRh  a  finely  drawn-out  glass  tube  into  the  perman- 
Kaiiate  solution  now  on  the  bottom  of  the  beaker.  Air  bubbl.>s  enclosed  in 
thf  oolored  li.mid  film  rise  throuch  the  nil  nn.)  bre-?.k  at  the  --.!;;-!■:•..•■:■  i-.:,.  n:-.=c 
of  the  expansive  force  of  the  gas.  Th.>  colored  water  drops  back  through  the 
oil  e.xa.-tly  in  the  same  manner  thai  a  balloon,  bursting,  drops  to  Ihe  earth. 


WIIV    is    KI.OTATKl.N  .' 


l.!!t 


Thfiv  aiv   at   j.ivM.nt   ..nly   tlnv,.   knoun    uavs  of   foivi,,..   ,    „,s 
'n-l.HMH.allv  into  .solution  so  ,|,a,  i,  aHually  ."upi.s  „,.    .nh-rsnrial 

■^''7if"*    •'"■   '''I""'    '" -"'-^    "'    '"-tine   ,.    in   .,,1,   ..invrs  or 

|...Mhs,  ,.s  ,.  ,|,.>,.,.,l„.,l.  ,or  instan,...,  ,„  tl„.  patent  papers  of  the 
Minerals  Separation  Co.,  u,„.re  ,>n,p..ll..f.s  or  ,...ntnfu.^.l  pnn.ps  are 
—'1:  'J;  .l.vniin,'  it  into  sn,.|.  nunute  pornon.s  tl.at.  I,v  eapillarv 
""■■■•..  It  IS  aetnally  taken  into  solution,  as  is  .lone  in  a  ('allou-  eell- 
;""'  '■'  '"tnulne.ntr  it  as  a  surfaee  tihn  .snrn.,n.,lin;j  a  jet  of  Hui.l 
by  .neans  of  snrfa.v  ...nsinn.  as  ,s  done  hy  a  .ne,ho,|  nniler  proeess 
<n    patent,  ■ 

'l''"'n-  .'uv  also  three  n,etho,ls  n(  expellins;  ,li.s.solve,i  jras  from  a 
'"'"  """  '"•'■'"■  vital  intere.st  to  the  matter  u>  haml;  (I,  Sup.r- 
saturat.oM,  so  that  the  e.vess  ...s  eo.nes  ont  of  i,s  own  aee 'nl ; 
'^  heatinf,  wh.eh  e.xpels  son,e  of  the  ....s  hy  inereasin,.  its  volun.e- 
nml  (.  ,  re,inrt,on  of  pres.sure.  The  j.resent  Kin,ore  maehines  work 
iH'  pulp  m  a  vaenum.  takin,.  advanla-v  of  the  faet  that  "'at  eon.stant 
•-'l-'-ature  the  ,...s  dis.solved  in  a  -nven  volun.e  of  li,,ui,l  varies 
direetjy  as  the  pressure"— Henry 's  law. 

Sinee  it  is  ea.sh.r  to  work  i^  the  open  air  than  in  a  vaeuu.n, 
flotation  maehines  nsins  ll>f  J.rineiple  mention.,!,  of  forei,,.-  more 
air  into  solution  than  tl,e  li,|ui,l  ean  hold,  are  preferahle"  The 
seeond  method  mentioned,  of  e.xpellin^^  dis.solved  ^as  hv  heat  ai.ls 
the  super-saturation  type  of  machine  in  two  ways:  (l)"„aseent  cas 
IS  expelled  Iron,  the  li,|uid  to  he  readily  attaeh..d  to  solids  for  tlofi 
tioii;  and  (2i  di.s.solved  gas  is  e.xpelled  from  the  solids  .so  that  -ms 
hul^.Ies  may  he  easily  attached  to  them,  llere^  lies  the  whole  see;et 
ot  flotation. 

Xo  soliil  ean  i)e  floated  unless  it  contains  some  dis.solved  r^as  Whv  ■> 
For  the  reason,  e.xplained  above,  that  the  envelopi„tr  'liquid  skin' 
.■annot  he  penetrated  or  hroken.  It  was  shown  above  that  a  gas 
bubble  ,s  surnn.nded  by  a  film  of  liquid.  A  solid  in  a  li,,uid  is  in 
tlie  same  way,  surrounded  by  a  film  of  the  liquid,  for  the  same  reason 
Therefore,  in  a  liquid,  the  molecules  composing  the  film  around  a 
gas  buhhle  would  have  uo  more  attraction  for  those  composing  the 
film  surrounding  the  soli.l  than  they  wouhl  \v.no  for  anv  molecules 
in  the  l„|uid  itself.  TTenee  the  bubl,lo  would  not  altai.h  itself  to 
the  solid.  It  is  seen  then  that  flotation  has  for  a  foundation  a  subject 
ot  which  practically  nothing  is  known— occlusion  of  gases 

It  is  self-evident  that  the  same  cause  which  ten,l«  fn  .„..„. 
saturate  a  liquid  with  pas  will  also  have  fha  same  tendencv"  to 
super-saturate  a  solid  contained  therein.     And  also  the  same  cause 


140 


'I'lii;  Fi.di- \riip.s   I'Hixi:.-.-, 


Ili.il  lrii,|.s  I,,  ,||s|„.|  r,-,„M  s,,hii„„i  ||„.  ,|iss,.l\r,l  kmn  uill  also  Innl 
t"  .iisprl  til,.  .;ts  lrn,u  a  s,,h,l  „,  ,|,,s  sainr  li,|m.|.  TJi.Trlun.  a  s„li,| 
"1  "  li'|iii,l  h<r,„n,s  a  iiu.-j.iis  lor  ||„.  lurmat  nm  ,,f  Iml.Mrs.  Tins  w 
c.-iMly  .IniioMstralr.!    I.y    t|„.    r,„„,alin„   ,,l'   vapnr  l.uM.l.vs  u  l,..„   uatn- 

is   linijiMJ, 

Thr  Mirrliar-iiii:  ,<\-  a    ii<,in(|    witli  a  i.Ms  l,.ri,ls  to  siuvliartf-  aiiv 
'^''"'   '"   ""^   l"l""l    ""   ."•'•"HMt    ni    ,l,;ruM(m.      Thr  a.llirsi,,,,   „f  II,',. 

l-MS  Inr  Ih..  sni,,|.  t  l.,T,.  t  m,v.  Will  ,..,„1  t,,  ,.,u„|..||v  tl,,-  ^ra.>  OH  tllr 
silMa.-,.  ,,(•  ||„.  sol|,l,  Sulli.Mrllt  .•,,i„|..„salinri  will  ,-,.ll,.,-t  ,.„„||.r|, 
>ii-lr.ul,.s  of  til,,   .as   t„    lonii   a   hul,l,|,.  „„    ll„.  siirla.v   „f  tlic  s,.ln| 

'■''"•    ■'*"' ■''■"•'■    'I""    '"    .liirilsion    ,,f    i.Ms    i,i    th,.    ,,,, posit..    ,lir,.r- 

"""•    "''^    '"'    I"'"' 'I    ''.V    '■au.siiiir    til.,    -a.s    I..    I x",,..ll,.,l    f|.,„„ 

'■'""''■  ""■  '"l""l  '"•  ■'  >^"li'l  '■ontain.',!  m  tliis  li.|,n,l.  Ati  ,.xanipl,. 
"!■  tins  IS  tl,.'  .Imnpins,'  „r  a  r,,l,l  ,„•,,  jnt,,  tli,'  hot  solution  ,,f  a  t|,,tatioM 

'''"'"•      '5"l'l'l''^  in iiMl.^ly     ,n,|    t„   f,,,-,,,   „„   ,1,,,   ,„.,,  part  ir|,.s.   I,v 

iVMs,m  ,,f  ,-o|„.su,.  a. Ml  a.lhrsiv,.  lon-.'s,  and  liav,.  ||„.  t..n,l,.n,.v  t,.  1,',. 
cnlarL'iMl  liy  tli..  <,'as  in  solution  in  th,.  lii|ui,l. 

It  is  natural,  tlicn^for...  to  suppos,-  that  s,.li.|s  with  hitrl,  „,.,.lusiv.. 
ix.w.u-  r,,r  i,'as,.s  hav,.  a  jrr.-at.T  t..n.l.'n,.y  to  tl,.al.  II,. r,',  th,.n  i.  a 
.■.•Ills,.  .,f  s..l,',.tiv,.  rt,,tation.  IF,v,,-kiah  Uni.llor.rs  patent  No.  :!4:,.|i.-,l 
IS   th,.    lirsf    t..    r..,-,ijrni/..    this.      S,„.akin-    of    m.^tallir    partii'L^s.    h,. 

stat.'s:      ••Th.s..    floatiii-    p,-M-tirl..s   a| ar   t..    p.,s.s..ss   .soni..    p.-ruliar 

'|u.-iliti..s  wlii,-li  n.p..|  water  Inun  th.-ir  surta.v.s,  ..sp,.,.iallv  wl,,.,,  su.'h 
p.-irtirh.s  air  .■.\p...s..,l.  ..wn  nioiii..ntafily.  t.i  attno.spii,.ri,.  air'."  Lat.u' 
liiis  ph,.nonicn.ui  .■aus..,l  troul.l,.  i,..  inst,.a.l  of  l„.|„.||tinsr.  H,.hn.n 
who  .says  in  his  pat.-ut  X.).  474..^i'f.,  an  infeivst  in  whi,.|,  is  as.siirn,.,} 
I"  CiiiTi,.  .1.  Kwrsiin:  -l  ...xp,.!  fnuii  su.'h  niin.'ral  an.l  niptal  par- 
tir|..s-tli..  air  an.l  otli.'r  -a.s.'s— l,y  pr..,iu.unjr  us  far  as  pra.'tiral  a 
vHcunMi--or.  aii.l  i)r..f..rably.  I.y  applyinfj  heat  to  th.'  .)re.  tln'rehv 
olitainin?  tlie  il.'sin-,!  oxpulsi.m  ..f  air  an.l  ..th.>r  iras.'s." 

Why  th.'U  ,io  niin.Tals  .h.u,.  in  tlu's..  pat.'nt  pap.-rs  tu.vinin.r  soli.ls 
'•""tanun-  uu-tan.  an.l  ..sp....ially  sulphi,!,-  minerals,  .vrlu.l..  .ms,.s 
more  r,.a.lily  than  ..th..r  s.ili.ls?  It  is  only  n,..-..s,sarv  t,.  l.,..k  int."  th,. 
suh.i.M.t  of  ..r,.  .l,.p,,siti.Mi  tor  th,.  answ,.r.  Primary  sulphi,],.  or,.s 
are  ei.an^^.il  n.ar  th.-  surfa.-,-  i,,  snlphat..s.  .•arh..nat..s.  o.xi.I,.s.  ,.t,., : 

^■■As  in  flu  ,.as,.  „f  li.i„ids.  we  would  expert  that  the  nmomit  of  •'■is 
;i<lh.'nmr  to  the  siirfaee  or  ahsorlied  in  the  pores  of  a  soli.i  wouhl  varv  with 
the  natme  both  of  the  .olid  and  of  the  gas.  with  the  extent  of  the  surface 
witli  ihe  fineness  of  the  iM.res  and  lastly  with  the  temperature,  berominR  less 
as  the  temi>erature  rose."     .losiah  P.  Cooke.  .Jr.     Themieal  Phv=i.=  • 

-He  uesentj.s  a  trav..li,ii,-  hWt  with  one  end  in  water  to  take  ad\antaKe  of 
this  fael.    This  antedaf^s.  and  is  the  same  principle  as.  the  Macquisten  tul...s 


\\  IIY    I-    H.<ll'  niilN  .' 


Ul 


iM  (pIIrt  wonls,  .Iniiural  iilli.iity  a.s.sisls  .siilp|ii,|,.s  in  al.sorhiiiK 
HNvtr,.,!  ,„■  rarhnn  ,|,„m,|,.,  11,. I,,-,,,,  an, I  oil,,.,-,.  ,|is,.,.v..n',l,  hy  tjio 
•'"'  "'  "!'■  ini'T,,.s,..,|„..  1 1, at  ni,,s|  iMiii.-ral  j.arlirh.s  t<.  !„•  savr.l  l,y 
'"ii'MMtratioM  l,av.-  laiw  r  p„ns  and  siinar,.,  „f  lar^^.T  ,.xt..nt  tliaii 
■•'I'lal  M/.'.i  •transruc'  |.arti,'l,.s.  Tiiis  f^iv-s  a  ^fivattT  clian.v  f„r 
L'a.s  ,M.,.|iisi,.n,  \vlii,.|i  is  an,,tli,.r  ..aii.s..  „f  s-'li-ctu,.  ri,)lati..n. 

Tliriv  IS  |)ra,.ti,'ally  no  a.lli.'sivr  f,n-rr  cNiMintr  l,ftw(...n  oil  or 
tattv  snt.sfaiii'.'s  an.!  wat,-r.  As  a  li.'n.Tal  rulo,  an  oil  is  hut  sli^'iitiy 
>olul,|,.  ,„  ual.T  Ul-  uatrr  Ul  oil.  Tli,.iv|-,„v  ^^al,•l•  uiU  not  adlu'iv 
I"  a  siirla,-..  wrtto.l  willi  oil  or  oil  mil  not  adli.Tc  t,i  a  surfar,.  .vetted 
"illi  wat.r.  Al.so  an  oil.  due  to  its  i.roi>,.rty  of  ,.a|.illarv  attraction 
lias  that  pow.T  of  ontrrinff  solids.  Therefore,  owing  to  larger  surfaces 
an.i  pon.s.  ia,,M  „ulals  and  siilpliidrs  arc  eapat.le  of  ali.si.rhins;  oil 
s.)  that  siitltieient  oil  can  he  attache,!  for  aL'u'loMi.ration  and  tlot.itinn. 
Tins  selective  Hotation.  as  nicnti, ,»,■,!  ah,.v..,  is  not  now  worth 
eon.siderin^',  h,-  ,nise  so  larne  a  (|iiaiility  of  oil  is  necessary. 

-Mickle's  experiments'  show,,!  that  no,,.'  of  th.'  niincrais  tri,.,l 
hoi.  ,.oI,|.  or  with  rcluced  i)res.sure  floated  on  oil  un,ler  anv  of  the 
'"iiditions  ^,U,■,■,■  ti,,alin-  would  fak.'  plac  on  water.  Tlii.s  was  to 
l)e  expci-ted,  since  the  specific  gravity  of  oil  is  less. 

What   th,.|i  is  th,.  p,,t,.nt    fa,.t,,r  for  s,.l,.,.|ive  ri,)tation.'     It   is  the 
'il'ilit.v  to  vary   tl„.  --angle  of  hystcn'sis'."     It  has  heen  ,s.v„   from 
th.'  ahovc  that  soli,ls  oc,-lude  gas  which  can  he  expelh'.i  from  tli.'m 
II    this  gius  he  expelled   from  them   when   tliev  are  in   a  licpiid  at  a 
time  when  gas  is  expelled  from  the  li,|ui.l.  thev  Ixvoiik-  the  nuclei 
tor  the  tormalion  of  gas  buhhics  which  will  float  them  under  .-ertain 
conditions.     Now,   Iheivfore,  if  it   he  possible   in  an  ore  i,    xture  to 
drive  out  a   considerable  portion  <,f  the  gas   from  all   the     .articles 
then    will  be  insiiffien-it  remaining  [n  the  'gangii..'  to  fl,,at' it   while- 
the   iiiiiuial   containing  m,)re  gas  will  float    to  the  surface.      It  has 
been  found,  for  instance,  that  sulphuric  acid  in  very  small  ouantity 
;id,lc,|    t,,    wat,.r   will   d.'crea.se   the   angle  of   hysteresis   to   that    i),.in't 
where  quartz  and  similai  •gangue'  will  .sink,  whih-  that  of  the  metallic 
particles  remains  practically  unchanged. 

Since  an  acid  in  very  minute  quantity  will  i)ro,iuce  this  etTect,  it 
is  not  due  to  rise  in  temperature  or  reduction  in  pressure,  which 
would  ,lrive  out  the  occluded  gas.  This  must  be  caused  then  by  no 
ordinary  phenomenon.  The  only  way  that  an  acid  can  act  in"  this 
manner  's  in  the  capacity  of  an  electrolyte,  especially  when  dilnte.j 


^Pi-oceediiiKs  of  the  Royal  Society  of  Victoria.     Vol     '3      Part  ■>  of  K.ll 
•-•Trans.  Inst.  M.  &  M.,  1912.  Presidential  Address  by  H.  L.  Snlirnn." 


142 


THE    FLOTATION    TROCESS 


U,  Its  dissociation  jHiint.  That,  is.  >:oini.l,.tc  i.mi/atiou  exists.  Vcl 
witli  this  e.\trenie  diliitioii,  gas  is  e.xpcllod  from  a  .solid  contained 
therein.  In  other  words,  eciuilihrimn  does  not  exist.  Wliy?  It  is 
on  aeeount  of  tiiese  ions  of  tiie  electrolyte  which  cause  thisdisplace- 
ment  of  equilihrimu  lictween  the  solution  and  tiie  giw  dissolved  in 
the  solids  within  this  solution.  This  then  resolves  il;se)f  into  a  siini)le 
ease  of  osmotic  pressure.  The  surfaee  of  the  solid  is  the  septum. 
The  ions  of  the  electn)lyte  enter  the  solid  whil.-  those  of  the  gas 
leave.  Since  the  carrying  solution  is  saturated  with  gas  already, 
bubbles  form;  and  this  action  continues  until  the  eutectie  point  is 
rcae'  "d.  .So  far  an  acid  (sulphuric  on  account  of  its  cheapness)  has 
been  used  as  the  electrolyte,  because  it  produces  such  a  great  change 
in  the  angle  of  hysteresis. 

In  the  future,  as  more  is  learned  concerning  flotation,  the  tiner 
and  more  delicat.'  manipulation  will  be  better  understood,  permitting 
an  alkaline  electrolyte  to  be  commonly  us(>d.  This  will  allow  of  the 
selective  action  for  irniieral  particles  other  than  sulphides  so  that, 
for  instance,  cerussite  or  malachite  .an  be  separated  readily  from 
gypsum,  quart/,  etc.  This  is  not  to  be  confused  with  Ilorwood's 
"differential"  or  "preferential"  ])roeess,  whereby  the  surfaces  of 
some  sulphiile  minerals  are  oxidized  by  roasting  to  prevent  them 
floating  with  another  sulphide  in  a  mixed  stdphi<le  o-e. 

^\  hile,  as  stated  above,  the  fundamental  requisites  are  the  manu- 
facture of  'life-preservers'  and  the  attachment  of  these  to  the  min- 
eral particles,  it  is  still  neces.sary  to  rescu.-  these  i)MrticIes.  ]}ubble.s, 
on  coining  to  the  surface  of  a  liquid.  Imrst  if  not  protected,  and  the 
attached  mineral  particle  sinks.  Why  ilo  they  burst?  (1)  Relief  of 
pressure,  so  that  tlie  contained  gas  expanding  <'\erts  more  pressure 
on  the  liquid  film,  (2i  adhesive  force  of  containe<l  gas  for  thi'  atmos- 
phere, or  (3)  evaporation  of  the  liim  causes  this  b.ursting.  The  greater 
the  super-saturation,  the  greater  the  interior  gas-pi(>ssure  of  the 
bubbles,  so  that  they  in  reality  exjilode.  This  is  the  case  with  bubbles 
in  a  glass  of  soda-water,  for  instance.  IIow  can  this  lie  prevented? 
The  small  boy  will  i)rcvent  it  by  coaling  the  bubbles  with  soap  that 
is,  by  toughening  llie  liquid  liliii.  This  then  is  the  secret  of  "the 
froth-forming  .iiateriar'  so  frequently  mentioned  in  the  varieus  patent 
papers  of  the  Minerals  Separation  comi>any.  Why  is  an  oil  the  most 
uset'ul  substanci'  with  which  to  do  tliis? 

It  has  been  shown  above  that  metallic  particles  are  readily  coated 
with   oW.      Theret*0!'e 


il 


...1.. 


cohesive  fon'c  is  exerted  on  the  oil-coated  mctalli.'  particles.     Bi^sides 


WHY    IS    KLOTAi'IUN  '! 


143 


an  fiivfl(ii)c  to  hold  tlic  i:n>.  ...i  atToiiaut  uses  a  mt  to  strengthen  his 
balloon,  so  that  when  tlic  pressure  is  relieved  by  tlie  higher  atmos- 
phere it  will  not  Imrst.  This  same  etTect  is  obtained  in  froth-flotation, 
in  the  same  way  that  particles  form  around  drops  of  water  on  a  dusty 
floor  and  prevent  the  globule  from  breaking,  small  particles  form 
a  network  around  tlie  large  bubbles.  This  is  due  not  oidy  to  the  force 
of  cohesion  of  the  oil  on  one  particle  for  that  on  another,  but  the  force 
of  cohesion  existing  between  the  particles  tliemselves.  Thus  a  frotli  is 
formed  of  bubbles  that  do  not  readily  break. 

It  is  a  well-known  fact  that  water  hiis  the  greatest  surface  tension 
of  all  liquids  under  ordviary  conditions,  except  mercury.  It  is  there- 
fore a  safe  assumption  tiiat  dilution  with  another  liquid  will  decrease 
the  su  'ace  tension.  The  tendency  to  float  is  decreased.  With  re- 
duced surface  tension  bubl)les  burst  more  readily.  From  this  it  is 
easily  feen  that  surface  tension  is  decreased  exceedingly  by  the  us<> 
of  a  volatile  liquid.  Alcoiiol  evaporating  from  a  substance  held  near 
a  bubble  will  diffuse  sufficiently  to  readily  dilute  the  surface  film  and 
quickly  burst  it.  Mineral  particles  floated  when,  for  instance,  amyg- 
daloidal  or  globidous  eucalyptus  oil  is  used  will  dance  on  the  surface 
of  the  liquid,  being  apparently  attracted  and  repelled  until  evapora- 
tion ha.=  progressed  sufticiently  t.)  equalize  the  surface  tension  not 
only  of  the  lifpiid  but  of  the  l)ulil)les  iis  well. 

Water  then  is  the  natural  and  universal  iredium  for  all  flotation 
machines  and  air  the  necessary  adjunct.  The  air  may  be  in  the  pores 
of  the  iruneral  particles  and  as  films  around  them,  so  that  they  are 
not  ea.sily  wetted,  in  which  ca.se  the  machine  may  take  some  such 
form  as  a  Macquisten  tube  or  Henry  E.  W^ood  type — a  purely  surface- 
tcn.sion  effect  into  wiiich  enters  notbintr  but  water  and  air.  The 
meniscus  of  the  water  buoys  up  the  metallic  particles  surrounded  with 
an  air  film  that  preveids  them  being  wetted.  The  force  of  gravity  is 
le.'js  than  thrt  of  surface  tension,  so  the  particles  float.  If  the  i)articles 
be  surrounded  by  a  watiT-film.  the  cohesion  of  the  molecules  of  this 
lilin  for  those  of  the  body  of  water  neutralizes  the  surface  tension,  and 
"lavity  sinks  the  jiartii-lcs.  Or  again,  minute  bnblilcs  may  be  attached 
to  metallic  particles  that  ne('(  ssarily  contain  occluded  gas.  A  thin 
film  of  oil  may  enclnse  nr  cont.nin  the  par'icles  and  Ihcir  attadicd 
bsibbles.  With  sutTicient  displacement  the  particles  will  rise  to  the 
surface  and  form  what  may  be  Icrmed  a  DeHavay  flo!>t.  Or,  lastly, 
the  tmbbles  may  bi'  large  and  have  the  mineral  particles  attached  to 
them,  as  veil  as  being  attached  f.  each  other.  This  is  the  so  called 
froth  flotation. 


144 


THE   FLOTATION    PROCESS 


WHAT  IS   FLOTATION?— II 

By  T.  A.  RicKAKD 
(From  the  iliiiimj  and  ticifntiftc  Press  of  October  2,  1915) 

All  of  the  iiatuml  pliuiioiiifiiii,  or  appearaiiL-cs,  ilescTibcd  at  the 
begnuimg  of  tli,.  previous  artiele.  play  their  part  in  flotation  and 
each  of  them  has  serveil  as  the  basis  for  one  or  other  of  the  many 
patents  that  have  involved  the  siihjeet  in  a  maze  of  vindietive 
litigation. 

Surface  tension  is  th.'  idr;.  underlying  Ilezekiah  Bradford's  patent 
of  1886.  Jn  this  process  the  dry  powderrd  ore  is  caused  to  meet  the 
surface  of  a  still  Inuiy  of  water,  so  that  the  metallic  particles,  which 
are  not  wetted,  are  made  to  float  away,  while  the  gangue  particles, 
which  are  wetted,  sink.  This  was  th<>  first  application  of  flotation 
without  the  aid  of  oil. 

In  1904  A.  1'.  S.  Jlacquisten  invented  a  tul)e  ai)paratus  in  which 
surface  tension  is  utilized  for  concentration.  In  1906  the  process 
was  applied  on  a  working  scale  in  the  Adelaide  plant  at  Golconda. 
Nevada,  where  chalcop>rite  was  separated  from  a  lime-garnet  gangue! 
In  1911  the  Federal  fining  &  Smelting  Co.  adopted  the  process  for  the 
Morning  mill,  at  JIullan,  Idalio,  in  tlie  separation  of  blende  and  galena 
from  a  (piartz-siderile  gangue.  At  Golconda  96  tubes  treated  125 
tons  per  day;  at  MuUan.  119  tubes  fivat  ir)0  tons.  The  iron  tid)e"is 
6  ft.  long  by  12  in.  diameter.  The  interior  is  ciist  with  a  helical  groove. 
The  tube  is  revolved  at  .iO  r.p.m.  Success  appears  to  depend  upon 
•  he  angle  at  which  the  melallh'  particles  are  presented  to  the  surface 
of  the  water.  Subsequently,  the  water  at  Golconda  was  slightly 
acidified,  so  that  it  nuist  have  caust>d  an  ebullition  of  carbonic  aeill 
gas  from  the  lime  in  the  ore.  Thus  the  bubble  phenomena  may  have 
come  into  i)liiy.  Later,  small  additions  of  coal  oil  were  made,  so  that 
another  i)hase  of  flotation  was  inlro(luce<L  In  tlie  first  instance,  how- 
ever, the  .Mac(inisteii  tube  was  a  real  surface-tension  i)roee.ss. 

In  l!tOr,  II,  L.  Sulman  and  II.  F.  K.  Picard  obtained  a  British 
patent  for  a  siiiiihn-  process,  but  it  was  a  failure.  As  the  floating 
particles  are  in  the  nature  of  a  film,  or  "in  patches  one  particle  thick." 
the  area  of  the  separating  surface  ha.s  to  be  large  and  still.  More-. 
over,  some  gangne-tiiinerals  are  floated  as  readily  as  the  metallic  parts 
of  the  ore, 

Tm  1912  II,  K.  Wood  (le.s.M-ibed  his  method  of  concentration,  by 
the  surfaee  tension  of  watei'  alone,  in  a  paper  rea<l  before  the  American 


WHAT    IS    Fr,OTATION  .' — II 


145 


Institute  of  Mining  Engincui-s.  In  common  with  otliiT  mutiillurgists, 
he  had  noticed  that  dry  particles  of  sulphide  minerals  are  "good 
swimmers."  In  all  gravity  work,  we  try  to  drown  them.  He  had 
also  proved  for  himself  that  the  oxides  are  easily  wetted.  Thereupon 
he  devised  a  machine  in  which  the  dry-crushed  ore  is  fed  in  a  thin 
stream  from  a  vibrating  plate  onto  a  current  of  water.  An  impetus 
IS  given  to  the  surface  by  small  water-jets.  By  retarding  the  current 
tlie  gangue  is  made  to  sink,  while  the  film  of  sulphid'^s  remains  on 
tlie  surface.  The  elasticity  and  tenacity  of  tliis  tilm  is  remarkable. 
The  process  is  being  applied  on  a  commercial  scale  to  molybdenite 
ores  by  the  inventor,  Jlr.  \Vood,  at  Denver.  lie  has  also  made  experi- 
mental demonstrations  0!i  grapliite,  tellurides.  and  other  lustrous  min- 
erals. At  the  San  Francisco  del  Oro  mill,  in  Chihuahua,  Jlexico,  12  of 
liis  nuichincs  are  in  use  on  an  ore  that  has  defied  other  efTorts  at  con- 
centration. 

IJi'LK-oiL  flotation  was  invented  by  Roljinson  &  (,'rowder  in  1894 
and  developed  successfully  by  Francis  E.  Elmore,  whose  British 
patent  wa.s  obtained  in  ISDS.  In  the  Elmore  i)rocess  the  crushed 
ore  is  mixed  with  several  times  its  weight  of  water.  With  this  pulp 
a  weight  of  oil  equal  to,  if  not  exceeding,  tliat  of  tiie  ore,  is  mixed 
gently,  so  as  not  to  break  or  emulsify  the  oil.  The  oiled  mass  is 
run  into  a  spitzkasten,  wliere  the  oil  rises  to  the  surface,  buoying 
tlie  metallic  particles,  while  the  ganguo  and  water  are  removed  at  the 
bottom.  Wliiie  oil  is  described  as  the  prime  agent,  it  is  probable 
that  air,  entrained  by  agitation,  increased  the  buoyancy  (if  the 
concentrate.' 

On,  .wn  AiH.  Coming  to  processes  using  a  combination  of  oil  and 
;iir,  we  have  the  Everson  patent  of  1885.  Carrie  J.  Everson  was 
\\;..shing  some  s;ieks  in  which  concentrate  had  been  shipped  to  her 
brother's  a.ssay-otTRce  at  Denver  when  .she  noticed  that  the  sulphide 
particl(>s  floated  on  the  water.*  It  is  said  that  the  sacks  had  become 
grea.sy,  but  it  is  quite  likely  that  she  used  .soap,  in  which  ,a.se  the 
greasiness  is  not  required  as  an  explanation.  In  her  proce.s.s  the 
maximum  addition  of  oil,  namely,  18";,'..  is  less  than  one-sixteeiitji  of 
the  quantity  required  for  bulk  flotation.     As  to  air,  that  she  olitaiiied 


'X  simKPstion  that  is  confiiiiied  by  the  statement  of  Walter  MrDermott 
that  "in  praetirc  [nf  the  p:iniore  process]  the  afiitation  with  the  pul|i  results 
in  the  oil  takins  up  a  very  apprerialile  quantity  of  :iir.  «ivin«  a  rertain 
sponginess,  with  natural  inrrease  in  floating  power."  'Thp  Conroniratton 
of  Ores  hy  Oil.'  /■;   .(■  .1/.  ,/..  Fi'liniav.   !4.  lOOl!.  paj-'e  L'tl2. 

•This  proves  to  have  l.pen  a  .arn.  See  pape  ,■{.-.  of  this  book  and  Thf 
I'^verson  Myth,'  Vining  and  Scientific  Press.  .January  15,  1!)I6. 


14C 


THE    FLOTATION    I'KOCESS 


I'.v  liif  .-iirilMlioii  .>f  til,-  pulj.  liy  niriiMs  nf  two  fans  i-jidiatiiis  from  a 
liolhiw  revolving'  iiiImv  Tlic  msult  a.vonlinu'  ti,  a  drscription  written 
111  I.SIMI,  not  ill  til.,  ii^'tit  of  piv.:ii(ii,v(l  observation  today— was  the 
fornuilion  of  a  ••thick  sc-niii  of  siilpliidcs"  that  •'row  to  the  surface 
and  was  sliiiiuncd  ofV.  Iravin;,'  tin-  liiiiicrto  l)lack  ore  as  wliiti-  as 
snow." 


Fl(,. 


rilK.    .lA.N.NKY    H.Or.MION     MACHINE. 


The  original  Inilk-oil  prore.ss  of  Klmorc  had  iiuinerous  applica- 
tions, some  of  which  were  fairly  successful,  hut  in  1!.I04  it  was 
displaced  liy  the  Elmore  vacuum  process,  in  which  flotation  by  hulk- 
oil  WiLS  suhorditiated  to  the  huoyant  etl'iM^t  of  air-huhhies  generated 
from  the  oiled  mixture  while  uiiiler  a  vacuum,  and  by  heating.    Under 

norninl    cruiditinnc    \V!it<»n    I-.,. I, It.    ;..    ^..J..*: i    .r    -:  1    . 

■■'■■':   -!"   .i;:u;iii;i  t;i  a:r  equal  10 

2.2";,    of  its  volume.     Thi,-  i.s  liberated  under  a  vacuum,  but  neither 
the  amount    of  air  released    (especially  at  high   altitudes)    nor  the 


WHAT    IS    FLOTATION? — II 


147 


(iiiiiiility  uf  (lil  used  surtiL-fS  to  cxplaiii  the  degree  of  flotation  aehieved, 
as  ineasiired  in  wei^lit  of  coiieeiitrate.  Tlie  pivsem-e  or  tlie  addition 
of  limestone  or  other  carbonates,  with  the  nsc  of  acid,  su<;>;ests 
till-  aid  of  bul)hh'S  of  g;is  other  than  air.  Tlie  i>roportion  of  oil  in 
this  process  has  been  decreased  gradnall.v  from  10  lb.  p<r  ton  of  ore 
to  as  little  as  2.7  li).  ]n>v  ton.  As  the  iiiixiiif;  involves  violent  ;.i;itation. 
it  secnis  inevitalile  tluit  entrained  air  plnys  a  pnrt. 

To  the  'oil  and  air*  process  \\l  .uist  add  that  of  Edmnnd  B. 
Kirby.  f(jr  which  jiatent  was  applied  in  l)e<Miidier  1!)0:{  and  frranted 
in  January  lOOti.  Kirby  experimented  on  ore  from  Rossland,  British 
Colnmbia.  He  used  a  large  proixirtion  ("one-fourth  to  three-fourths 
iis  mu"b,  by  weight,  as  ore"i  of  oil;  he  added  aeid ;  lie  einph)yed 
heat;  he  "thoroughly  agitated":  he  "in.jeeted  air  into  the  mass"; 
and  he  obtained  "a  floating  .scum  of  hydrocarbon  liquid,  air.  bubbles, 
and  coiicentrat(>s  "  In  the  light  of  later  events  it  is  claimed  that 
he  must  have  made  a  'froth,'  because  the  oil  was  insunicient  to 
cau.se  bulk  flotation  and  the  agitation  sutiticed  to  entrain  enough  air 
to  produce  a  froth.  To  this  the  patentees  of  the  so-called  'agitation- 
froth'  process  re|)ly  that  his  "scum"  was  not  a  "froth"  in  tin  ir  sen.se 
of  the  term.  That  he  produced  froth  seems  highly  probable;  but  t" 
say  that  '.scum'  and  'froth'  are  the  same  thing,  is.  in  my  opinion, 
not  correct.- 

BuBULKs.  Meanwhile  the  bubble  methods  of  f  narles  V.  Potter 
and  Ouillauie.e  D.  Delprat  had  been  patente  i  in  l!l()2.  In  these 
processes  gas  was  chenncally  generated  witli  a  view  to  ])rom(iting  the 
flotation  of  metallic  particles  in  Broken  Hill  ore.  This  Australian 
ore  contains  calcitc.  which  by  the  addition  of  aeid,  emits  bubbles 
of  gas  that  adhere  to  the  sulphides.  Potter  used  acid,  agitation, 
and  heat,  while  Delprat  employed  a  hot  solution  of  salt-cake  or  acid 
sodium  .sulphate  and  sulphuric  arid.  Both  pnieesses  were  successful 
on  a  large  sciUe,  particularly  Delprat 's,  which  is  still  in  use  at  the 
Broken  Hill  Proprietary  mine.  Neither  used  any  oil.  The  bubbles 
Mtt;ich  themselves  to  the  sulphide  (blende  and  galena)  particles  and 
carry  them  to  the  surfa. ,  .  whence  they  flow  with  the  liquor  into  a 
compartment  where,  the  bubbles  lin-aking,  the  metallic  freight  is 
dropped,  and  cullectcd  as  a  mixed  concentrate.  T.  J.  Hoover  says' 
tli.'it  "the  result  of  the  manipulation  to  which  the  material  is  subjected 
='Scum'  is  the  impu.ity  or  extraneous  matter  tliat  rises  to  ttie  surface  of  a 


molten  lead.     'Froth'  Is  a  niultlplicit.v  of  bubhlcs, 

'ToncentratinK  Ores  b.v  Flotation.'     Second  Fdition.     Paue  101. 


JrMJ    Oil    il    UilLll    Ul 


148 


THK    FLOTATION    I'KOCKSI 


IS  tlu'  lormatiuii  ,.i  n  dense  froth  of  Imhhles  ami  niimTal":  lait  this 
was  puhlishr.i  in  1 !»]!',  a.ul  must  1...  read  in  tlie  lifrlit  of  events  1,,,,^. 
suhseqiieiit  to  the  eiaiiMs  made  hy  either  Totter  or  Delprat.  In  order 
to  explain  the  making  of  froth  without  oil,  he  su^trests  the  presence 
in  the  ore  of  sue],  suhstanees  as  •'yirld  ^'ummv  ortrani,-  .■ompounds 
that  selectively  adliere  to  the  ore."  This  is  an  imj.ortant  su^'gestion 
He  that  as  it  may.  the  Potter  and  D.'lprat  im^thods  d.mmnstrate  that 
flotalKm  IS  i)raeiirahl,.  hy  the  aid  of  hnhi,]rs  without  the  addition 
of  oil. 

In  tlie  Fronient   |.ni,.,.ss.  patented  in  (ireat    Britain  and   Itaiv  in 
June  lf302.  the  ])ul.hl,.  id,,,  i.s  dominant,  for.  while  Aleide  Froment 
used  od.  he  employed  it  to  attraet  the  l)ul.hles  of  ^ras  !.'enerated  hy 
the  reaeli.m  between  a.'id  and  cah'ite.  aildin;;  tlie  latter  if  .suitahh- 
earhonates  were  laekinir  in   the  ore.      He  emphasized   thr   f;i,.t   tliat 
not  (mly  have  tiie  lustrous  metallie  partieles  an  atTinitv  for  films  of 
oil.  hut   the  oil  itself  attracts  luihhies  of  jra.s.   hoth   air  and  earhon 
'iioxide.     He  reeommends  miK'h  less  oil  than  had  hitherto  been  used 
Jiamely,  a  "thin  layer  of  oil."  whieli  has  been  interprete.l,  aee,,rdinfr 
to  the  exirreneies  of  litigation,  to  mean  anything  from  less  than  1'? 
up  to  14^;,  ae.ordiiifr  as  the  Froment  patent   was  bein<r  uji'ehl  or 
attacked.    In  Froment 's  later  instnietions  to  the  piirehasers  (  Minerals 
Separation,  Ltd.^   of  his  patent   he  mentioned  the  quantity  as  fi-om 
1  to  3J%.     For  a  5%  swli)hide  ore,  the  oil  would  weifrli  20  lb.  per 
ton.     This  qui'sticm  of  the  quantity  of  oil  required  by  Froment  has 
been  much  discussed,  but  the  dominant  idea  in  his  mind  appears  to 
liMve   b.vn    the   at^inity   of   oile.l    partieh's.    necessarily   sulphides   or 
lustrous  metallic  particles,   for  bubbles  of  pa.s.     These  h,.  obtained 
liy    ajritation     (air-bubbles)    and    by    adding    both    acid    and    cah'ile 
'buhliles  of  carbonic  acid  gas)  to  the  pulp.     As  to  what  ''a  thin  hiyer 
of  oil"  may  mean.   I  do  not  know  what  Froment   interub.d  bv  the 
cxprcs.sion.  but  the  scientific  meaning  of  the  phrase  is  indicated  by 
the  fact  that  oil  when  droi)ped  on  the  surface  of  water  will  spreaii 
out  in  a   film  one  molecule  thick.* 

The  agitation  of  the  ingredients  specified  by  Froment  will  pro- 
du.'c  a  froth:  therefore,  to  the  detached  onlooker,  it  is  dit1i,-ult  to 
distinguish  the  ..s.sentials  of  his  process  from  those  claimed  in  tlie 
basic  patent  of  :\Iiiicrals  Scparaficm.  Mr.  Sulinan  called  the  Froment 
froth    a   "tende:'   ami    evanescent   as.semblage    of   bubbles   of   carbon 


■wn    r-nnisuii    v\  ,iirr  ;iii(l  ..;,   M.rciii  y.'    liy   Henri    Ucviuix.    TniM-.l:,tr,l  :,,ul 
jiuliiishpd  in  Annual  Rei)ort  of  SmitliRonian  Institution,  llM.I     ANo  1/   .(   v    /> 
■lni\   :!I,  im.".,  ii.-iRc  i.-.r. 


W  II AT    IS    FLOTATION  .' — II 


149 


(lioxiil.-  caiiyiii^'  iiiiii.Tal."  but  if  it  carriiMl  niiii.Tal  I  do  not  set;  tliiit 
liis  i-ffiisal  to  call  it  -rrotli'  is  of  any  frivat  (•.)iis('(itieiiL'e  to  those  of 
UN  who  are  not  iiitmst.il  in  the  liti-^atioii. 

<nA(;r  LATiiiN.  Here  We  come  to  what  is  apparently  a  break  in 
the  se(|iit  nee  of  inventiveness,  for,  lieginning  with  November  1!)02, 
Al-tlnir  Iv  CatterMioJe  obtained  a  sueeession  of  patents  for  a  process 
in  which  the  idea  of  oil-selei'ti((ii  is  used  to  sink  tli.>  iiietallic  particles 
of  an  ore,  not  to  Hoat  them.  To  an  acidified  pulp  he  added  from 
4  to  tj';  "of  the  wei>;ht  of  metalliferous  matter  present,"  not  of  the 
ore  as  a  whole:  therefore,  with  a  V2'/c  zinc  ore  this  would  mean  0.48 
to  0.72';.  say  10  to  lo  lb.  oil  per  ton  of  ore:  ami  with  a  '2';,  copper 
ore.  it  would  iiiejin  only  H  to  2]  lb.  of  oil.  iJut  this  oil  "is  brought 
into  the  condition  of  an  emulsion  in  water  containing  a  small  per- 
centage of  soap  or  other  emulsifying  agent."  Thes«'  are  the  words 
of  his  most  im])ortant  i)atent.  V.  S.  \o.  777.27:),  dated  December  i;{, 
lI'iU.  but  in  his  tirst  patent,  British  No.  2t),2!t.'),  of  November  28. 
l!io2,  be  gives  the  proportion  of  .soap  as  2"";.  When  this  mi.xture  of 
ore.  acidulated  water,  and  soapy  oil  is  agitated  violently  the  metallic 
particles  are  agglnmerated  into  tloci-ulent  ma.s.ses  that  sink,  the  sep- 
aration from  the  gangue  being  then  ctTei'ted  by  an  up-current  of  water. 
To  facilitate  the  .sejiaration,  the  mixing  was  conducted  in  two  stages, 
of  which  tlie  second  is  said  to  have  been  "a  rolling  foi'm  of  agitation." 
Cattermole  called  his  agglomerate  a  'granule';  Froinent  called  it  a 
"spherule.' 

FiiOTii.  The  Minerals  Separation  company  was  organ ixed  in  100.3 
to  acquire  the  Cattermole  invention  and  1hereaft(>r  his  patents  became 
part  of  the  property  of  that  company.  The  first  and  only  plant  to 
iisr  the  Cattermole  process  was  erected  on  tlu'  Central  iinne  at  Broken 
Hill.''  where  it  was  soon  displaced  by  the  so-called  agitation  froth 
process  of  Sulman,  I'ii'ard,  and  Ballot.  The.se  gentlemen  have  testi- 
fied that  they  made  their  discovery  b\  ev|)erimcnting  with  the  Cat- 
termole process,  api)lying  .scientific  methods  of  research,  based  on  the 
fact  that  .sometimes  'Moose  floccu,.  nt  mas,ses  of  partially  granulatcil 
sulphides"  would  rise,  instead  of  sinking.  Finally,  they  decided  that 
this  was  due  to  in.suflicient  oil.  The  actual  experiments  were  made 
by  Arthur  II.  Iliggins.  who,  by  diminishing  the  amount  of  oil  to 
0.()2%  on  the  ore.  cau.sed  so  many  of  the  metallic  particles  to  ri.se  that 
a  high  recovery  was  obtained  by  flotation.  IF.  L.  Sulman  says  that 
r.y  rfuucirig  Tiu-  aimiiiol  (li  uii  iiic  ^ranuiaiion  was  stop[)e(i  and  "co- 

•■■'Flotation  at  Brofsen   Hill.'     By  .lames  Hebbani.     Miinnfj  ni.d  Seirntifie 
Pr,-\s.  Sfptembei-  t.  liM.'.     See  paup  tin  of  tliis  boolv. 


150 


TlIK    FU)TATI()N    I'HOCKss 


".-hlrntally  n  niiii.Tal  ln,il,  lu-gan  lo  takr  its  phi.-e.-'  Tl.is  was  in 
Marcli  m-,.  WluTcMip.,.!  tlie  Uritish  patonl  of  .Minerals  Sopaniti.w.  N.. 
<N);i,  „1  April  11',  IIH).-,,  was  tak,.n  .ml  l,y  II.  L.  Su|,„an,  II  K  K 
I'lcard,  an.l  John  Ballot,  and  sulisr.pirnllv  Ihrv  ol.taincl  the  [  S 
I'atent  No.  8;i5.1L'0  of  May  2'.K  IIMC,.  issued  on  Xoveniher  f,  IIMW  '  h, 
this   patent    relVrene,.   is   made   to    tiie    CaUeriMole   patent    anri 


It      IS 


1,022,085. 


««T  or  courts  rkATioN  pi  mstkAL  soesuNas, 

*rrLll-iTI(.II   TILED  lOV    10    1^11 


I'atiTittd  Afir,  2.  iai:j 


Fig.  28.     j.^csimilk  ok  iivnt's  p.mkm 


.1-,   A.S   USED  AT  THK  tU  TTK  &   Sl'PKRlOR   MINK. 


WHAT    IS    FLOTATION'? — II 


151 


cliiiiiifd  that  the  'fjraniilatioM'  uharactfriziiiK  his  nictho.l  is  stopped 
liy  re.iiieiiig  the  ainouiit  of  oil  lo  "a  fraction  of  1%  on  the  ore"  and 
that  by  vij,'(!rous  a^'italioii  Ihe  oil-coated  particles  are  caust'd  "to  rise 
to  the  surface  of  the  juilp  in  the  form  of  a  froth  or  scum."    The  use 
of  'scum'  here  is  unfortiiniite  for  Minerals  Separation,  for  it  tends  to 
identify  the  'fmth'  made  hy  tids  process    ,  ith   the    sciuir   made  l.y 
most   of   their  i)iedeccssors  in    the   art.      In    tins  patent    ai'idulatod 
water,   warming  of  the   mixtnre.   olci.-  arid    from  0.02')   to  O.^y,^   on 
the  ore,  oleie-soap  solution,  th.-  formation  of  the  froth,  and  the  sep- 
arating of  the  froth  from  the  remainder  of  the  solution  are  specified. 
Since  this  patent  was  issuc.l  the  process  has  hceii  applied  successfully, 
and  on  a  large  seal.',  in   many  parts  of  the  world,  notahiy   Mroken 
Hill,   (ireat   Cohar.   (ireat   Fitzroy,   Chillago.-,   and   Wallaroo,   all   in 
Australia;  also  the  Uradeii  copper  mine  in  Chile;  and  more  recently 
at   the   Inspiration.   Anaconda,   and  other   important   mines   in    this 
country.     It   is  proper  to  add  that  a  froth-tlotation  process  is  used 
successfully  at  the  Hutte  &  Superior,  Mnuni.  and  other  mines,  hut 
the  users  deny  that  it  is  a  metli.x]  to  which  the  .Min.'rals  Separation 
company  has  propiietary   rights.      The  .litference   of  opiinon    is  yet 
to  be  settled  by  the  Courts. 

In   the  foregoing  review.    1   liave  omitted   reference  to  a  number 
of  flotation  patents,  some  of  them  intcr.'sting,  because  the  multiplica- 
tion and  repetition  of  detnil  would  be  only  eoiifusiiig.     It   will  be 
noted  that  the  amount  of  oil  per  ton  of  ore  ha-s  decreased  from  over 
a  ton"  to  less  than  half  a  pound.     Prom  an  insistence  upon  the  use  of 
acid  in  all  the  patents,  even  to  the  liust  quoted  in  the  above  summary, 
we  come  to  the  recent  fact  of  flotation  in  alkaline  solutions.     Indeed, 
in  the  case  of  the  Mexican  mill  we  are  told  that  the  deleterious  effects 
of  soluble  sulphates  was  overcome  by  an  excess  of  oil.'     How  much 
of  the  oil  used  in  the  prior  art  was  due  to  excess  of  acid,  it  remains 
to   be  stated   by   an   independent   investigator.      Much   of   the   early 
work  with  flotation  was  done  on   Hrf)ken  Hill  ore,  which  contains  a 
notalile  proportion  of  earbmiates.  hence  the  addition  of  acid  proved 
a    help,    by    generating   gas.    not    only    in    the    Potter   and    Delprat 
processes,  but  in  others  also,  namely,  tho.se  using  oil.    One  ingredient, 
however,  has  gained  progressively  in  in.portance:  air.     Other  gases 
have  had  their  day.  some  generated  chemically,  others  electrolvticallv, 


■•iNoicK   on   the    Knnore   Concentration   Process.'      By   Charles   M.   Rolker. 
Trans.  Inst.  M.  &  M.,  London,     Vol,  VHI,  1S99-1900,  page  382. 

■Mining  and  Sci<'iiti/ic  Press.  July  24,   1915,   page   124.     See   page  94  of 
this  book. 


152 


THE    ri-OTATiMN    l-KOCti-^S 


liiit  HI  llif  liilfst  ])li;isf  (,r  III,,  pniciss  tlif  iH'iiiif  air.'iit  is  air.  liui.'i-il. 
tlic  ffood  ifsiilts  fiisuin^'  Innii  llic  i.-ssfiicil  iinipoitioii  »(  oil  niiiy 
'"•  ''ii''  '"  "i''  l''"'i  lliat  llic  Irss  til,.  (,il  til,'  srivat.T  the  iiitcii.>sity  c.f 
a!.'ilaiii)/i  iv(|iiircd  to  spread  it  tliniuu'lmut   ih..  pul|).-     Tt.,'  vii,'()i s 

H.  L,  SOLMAN,  H.  H.  GHRENWAY  4  A.  H.  HIGGINS, 

ORE  COSflNrHATION. 

ArrLECATioa  tin:}  apk  iS,  ijoa 

962,678.  PaU^uUil  Juiie  2S,  1910 


/y  /■ 


.  rrt. 


l\ 


ft' 


/i     /■■  ^    f    "   n  \ 


i'lli.  Z'.K      ONE  or  THE  MINERALS  SEPARATION  PATENTS. 


»Du(ll(>y  H.  Norris  has  several  patents  for  the  use  of  water  contaliiinB.  in 
solution,  air  under  hi.Kh  pressure  for  intensifieil  hulil)ling,  with  or  without  oil. 


Wll  \'l 


rr.()i'.\ri(i\  ' 


l.VI 


af,'itutioii,  s..  .,n,.n  .•nq.liiiM/rd,  niiiy  liav  Imm'.i  likr  !„.■  slini  thai 
WiiN  jiiiiR'.i  at  III.,  rniu  iuul  kill,,l  il„.  piur,,,,,,  f,„.  jt  ,„i,.st  have  done 
"n|ivll,.Mn,iMlH.i„i:n.,|i...,ls:,t  nsi.lt..,!  ,u  .M.ra.M.M^' and  ato,„i/inK 

'^  '"''«^'  ^■"'""' ■  •"•••      'I'hr  lat.T  hist..ry  <,(  Hotatioii  siiK^'.'sts  that 

a   day   may   .•(,ni..   wlic,    tli.   oil,    lik,.   the  uuid,   will  be   found   non- 

.■s.s,.„l>ai,  and  in  its  ph.,-,.  u.ll  l„.  a,| I  th,.  i.iir.v nt  that  sM,,ph..s 

the  suhstan..,.   n.-piiivd   i„r  niakint;   l,iihhl,.s.     To   make   l,uhhl,.s  the 
surla.-..  tc.nsion  ,.r  th,.   ual,r  in   th,-  tl„tali,.n  ....jl   must  !„.  ,le,.i-eased 
\>y  a  e,.ntamuiaMt   ami  at    tli,-  sam,-   lim,.   tlie  viseositv  of  th-  li.piid 
nnist  be  Mn-n-tlien,-.!.     Oil  is  not  th,-  only  si.bstanee  that  ,.an  p,-rform 
th,-se   fun,.ti,.ns.     Sn„i,.  aikalin,.  ,-ompoun,i   may   Ih-   foim.l  that   will 
dojlu.   tn,-k.      In   ti,,.   CatL-rmoh-.   Suhmm   &   i'i.-anl  patent    {V.   S. 
/77,274>    a   fatty  a,-i,l   is  pi-,,(!n<-(,|   in  .ntn.     hi  another  patent    by 
Sulman.  (ireenway  &  lli-'ins   (  T.  S.  '.n\2XuS)   a  elaim  is  made   foV 
an  ..rtranie  eomp,)iin,|  ,-ontain,-,l  in  .solntion  in  the  a,-i,lill,.d  wat.-r" 
as  a  soluble  frothinjr  a-ent.     In   I'.  S.   l.()r,r,.4!ir,,  S,-hi,-k  elaii.is  the 
us,,  of  earbon  teti-a-,-hl,>ri,|,-  to  i).-omot,.  '  lcvi-ati,)n,'  or  Hotation.     In 
I  .   S.    TTO.tif)!),   Seammell   emj^h.ys  sulidiur  dioxide   as  a   means    for 
in,-n.asintr  th..  viscosity,  an.i  in  U.  S.  744.;{22,  Foote  uses  slaked  lime 
Amonjr    other    nostrums,    ah^ohol.    ,>henoI.    eamphor,    amvl    ae.-tale 
he.izoic  and  laetie  a,-i,is.  an,l  eah-ium  ,.hlori,ie  have  be,.n"  suggested 
111   various  patents.     In   s,.me  <.a.';..s.   possibly,   an   ingre.lient  of  the 
ore  1I.S..U  may  sufli,....     M..ainvhile  th,.  element  of  time  ,-s,sential  to  a 
good  tonnation  of  froth  siiKg,.st.s  that  the  delav  is  u.seful  in  inereasing 
the  viscosity,     Mere  speed  of  agitati,.n  and  aeration  .Lies  not  seem 
to  .sufTu.e.     But  sub-divi.sion  of  th,.  air  helps.     This  reminds  us  that 
T.  J.   Hoover  and  Minerals  Separation  t,)ok  out  a  patent,  in  Oreat 
Britain  in  1010,  for  the  intro.luetion  into  the  oiled  pulp  of  air  an.l 
other  ga.ses  through   a  perm,.able   medium,   but   it  was  not   <l.>emed 
w..rth  while  to  obtain  a  patent  in  th,.  Tnit..,)  States.    Knowing  nothing 
about  tins,  J.  M.  Callow  hit  up  n  the  same  idea  and  designed  the 
porous   bottom    now   in    use   at    many   flotation    plants.      Cattermole 
u.s,..l  an  ordinary  eone  or  fiabbett  mi.x.'r'  titted  with  baffles.     Fnunent 
empbiye.l  a  mix..r  of  the  egg-beater  type.     Sulmaii  &  Pieard  in  one 
of  their  patents   (V.  S.  793.S0S)   sugg...st  an  agitator  ma.ie  of  a  eoi] 
of  perforate,!  gas-pipe,  through   which   compressed   air  and   oil  are 
fed.     Centrifugal  pump.s.  Pachuea  agitators,  air-jet.s.  and  pans  with 
mechanieal  .stirrers  luuv  been  adopt,.,!  by  various  !!>v,.!..tn|.^      (Mh^j, 
devices   for  .-ausing  agitation  and   promoting  aeration   of' the  puhj 
Iiave  been,  am!  are  lieing.  introduced. 

"See  FiK.  41. 


l.')4 


TlIK    FLOTATION    I'KOCKSS 


SURFACE    TENSION    AND    SALTS    IN    SOLUTION 

I  From  (h,.   Uoio/r/  n,„l  Srimtifir  I'n'.sa  of  Octolmr  y,  lyir,, 
'I'lir   Kiliti.r: 

Sir— In  .Vdiir  c.litori;.!  (,ii  'Fl„tati,.ri  iit  Itrok.i,  I|.|r  ,„  v,)m-  issii,. 
M  S,.,,toinlM.r  4,  l:)l.-,.  ,,ai;,.  ;14.{,  y,,,,  ma,|r  a  statnucnt  n.^^Mnlinj; 
siirlac..  trnsinn  that  is  ratli.T  licnwinir  f.  a  sluWrMt  of  riotati,m 
It,  IS  as  lollnvvs:  ••Mr,  llrhhani  says  that  th..  sinfa.-e  tei.sio,,  was 
iMnvrs,..i  l,y  the  salts  iiitrod-  ;,1,  hut  u,.  venture  to  outmost  that 
tlic  op|>ii.sitf  was  the  fact." 

Surfac."  tofisioM  lias  Im.mi  tlin-sh.Hl  .,ut  |iretty  thorouplilv  l.y 
articles  appearing  in  the  Journals  of  the  A.neri.an  Chemical  Society, 
I'cfjinniiij,'  in  IHOS. 


•leiir.  Am.  Chilli.  Soc,  Vol.      XXX,      No, 


XXXI  It, 


XXXV. 


;!,     Miirtli 
7,     July 
3,     March 
"),     May 
7,     July 
10,     Octoher 
November 
December 


11, 
12, 


190H 
1908 
1911 
1911 
1911 
191.3 
1913 
1913 


These  articles  deal  with  the  drop-wei^'ht  method  (Weight  of  a 
fallini;  drop,!  for  the  detenninatiou  of  molecular  weight,  critical 
temperatur.-,  and  surface  tension,  and  they  descrihe  the  apparatus 
used.  The  work  «as  started  hy  Morgan  and  Stevens,  who  wi.shed 
lo  investigate  what  had  become  known  as  the  law  of  Tate. 

late,  in  18(J4,  had  made  a  generalized  statement  about  the  relation 
of  weight  of  drop  to  diameter  of  tube,  the  weight  tliat  eould  be  raised 
liy  capillary  action,  and  the  temperature  of  the  droj).  Some  of  their 
conclusions  are  that : 

u;i  The  drop-weight  of  any  liquid  is  proportional  to  the  di(.meler 
of  the  droi.ping-tube.  These  tubes  are  iinifrom  in  diameter,  thus 
dithering  from  the  ordinary  burettes. 

(b)  The  weight  of  a  drop,  other  things  being  the  .same,  is  propor 
tional  to  the  surface  tension  of  the  liquid. 

(c)  That  it  is  possible  to  calculate  the  temperature  at  which  the 
drop-weight  would  become  zero,  namely,  the  critical  temperature  of 
iiie  Jiquiu,  for  at  liiat  [loint  the  drop  would  disappear,  there  being 
no  distinction  lietween  the  gas  and  the  liquid. 

In  tlie  course  of  these  experiments  the  surface  tension  of  a  number 


■SIKKACK   TKN^ION    A.sr)  SAI.rS  IN    sou  TION 


io:> 


olorKUiiK;  li(|iii(ls  in  a<iiUM)u.s  sniinioi,  was  ilclcriiiiiicl  l,y  drop-w.-iKliI 
uiiil  found  t(.  raiiKt"  from  21  up  to  that  of  Wjitc-.,  The  tal.ulat.'d 
nsults  fovir  several  murs  in  the  Journal;  I  have  .•oi)i..,|  a  part  and 
condensed  into  one  lalilc,  which  is  given  ludow. 


AijiKors  Solutions  at  30 'C, 


(•.000 

<l.!t7» 

1'.143 

4.994 

10.385 

17.979 

23.000 

50.000 

75.000 

100.000 


Klhyl  alcohol. - 
3ur.  ten. 

7l.o:!o 


«5.«()U 
t;0.847 
53.137 
44.ti«8 

37. .ni 
:;2.941 
2«,521 
23.850 
20.75G 


0.000 

1.011 

2.500 

4.097 

9.994 

10.000 

25.000 

.-.0.000 

75.000 

100.000 


•Mi'thjl  alcohol.- 
,'e  Sur.  tPIl. 

71.030 


08.120 
«4..S45 

f!0.2'J4 

5:i.t;<;i 

48.817 

41. soy 

31.843 
20.173 
21.037 


-Aiiiyl 

alcohol.    , 

'  f 

Sur.  teu 

o.ouo 

71.030 

0.250 

53.712 

0.500 

4>'..I57 

0.750 

41.247 

1.000 

37.031 

1.500 

32.504 

2.00O 

28.6i>7 

2.498 

25.72i; 

^— Act'llc  acld.-^ 
','e  Sur.  ten. 

0.000  71.030 

1.000  07.750 
2.47.-  03.995 

5.001  59.435 
10.010  -.3.500 
14.980  49.451 
20.090  40.455 
49.900  37.109 
79.880  31.026 

100.000  25.725 

h  IS  to  !)e  noted  tl 


0  too 

I.'JOO 

2.500 

5.000 

10.1100 

15.000 

25.000 

50.000 

75.000 

-.00.000 


lOo.OOO 

Korniic  arid.— > 
Sur.  ten. 
71.030 


22.296 


69.816 
08.024 
05.706 
62.061 
59.197 
55.190 
48.112 
41.990 
35.281 


liiit  in  all  eases  the  very  iirst  addition  eauses  a 
very  considerable  lowering  of  surface  tension.  The  decrease  in 
the  surface  tension  of  water  caused  by  Ijie  addition  of  a  very  small 
amount  of  amyl  alcohol  is  especially  striking.  Thus  the  presence  in 
solution  of  even  s<i  small  an  amount  as  0.25%  changes  the  .surface 
tension  of  water  from  71. U3  to  5;j.7,  or  nearly  25%  at  30°  C. 

Morgan  and  Schrannn  studied  many  concentrations  of  a  few  salts. 
They  selected  the  molten  hydrated  salts  for  this  purpose;  those 
salts  which  melt  below  50=  in  their  own  water  of  crystallization 
being  especially  satisfactory  for  this  purpose,  for  the  reason  that 
<'oncentration  in  some  of  these  eases  could  even  be  carried  to  super- 


ftntorfltinn 


In  the  case  of  the  salts  which  they  studied  it  is  plain  that  surface 
tension  is  increased  by  the  salts  introduced.    Where  calcium  chloride 


41 


156 


THE    FLOTATION    TKOCKSS 


WHS  used,  tliL'  surl'iUT  tcnsioii  w;,.s  iiiciviLseil  fi'oiii  71  (KJ  \„  10"  37 
ai'P'-"xin.at,.|y  oO',.  T.kintr  a  trw  s,H.,.iti..  ..asrs  if  is  Mot,.,l  that  to 
iniTfHsc  tlu-  snrf.K'o  tt-nsidii  10^;   it  would  take 

I'O',;    CaC'l,  at  ;i() 
43';:   '/Ai   (NO J  at  45" 
21)';    Xa.CrO.  at  :Hr 
M';    Xa.SJ)    at  4(1' 

Till'  diagrraiii  is  appfiidrd.     Scr  Fi^r   ;}o 


S    /O   /S  20   25  30  3S  ^o  4S  SO  S3 

Gm.    so/rper/OQ^rr,.  so/ur,on 
Fio.  30. 


I  he  dcgiv...  01  arrui-a.'.v  ol'  \-al.so.i-s  ual■l^  ■  iKTaiizatio,,  tliat 
.•.iiuvakiit  sa."  solutions  c^xliihil  i.lentieal  valiu-s  of  s.irla.-e  tfiisio,, 
IS  shown  l,y  plottin-  the  san.o  ri-sults  reuu.-cd  to  n.ol..cnk.s  .,f  wat.T 
to  .nol.Miiles  of  sa'*.  But  one  must  he  caruful  not  to  earrv  fr.neraliza- 
tions  too  far  iR.,.ausc  this  .Iocs  not  liold  with  some  salts.  Tiu'  diagram 
IS  appended.    Sec  Fig.  31. 

The  fact    IS   liiat   s ,■  salts  .levate   wliilc   „t|„.r  d,.,„vss  surfaee 

tension,  hut  the  form.r  predominate.  In  addition  to  tiie  .salts  just 
mention..!,  tiie  tartrates,  earhonat,..s,  oxalates,  citrates,  lactates,  and 
a  i)art  or  tiie  acctat.s  rais«.  si-rlWe  tensi.m ;  uliile  the  salicilat.s  tl„. 
lmtyrat..s.  ,.art  ..f  fl,,.  a.-.-tates.  and  all  the  a.-i.is  lower  surfa.-,.  t.-nsion 

It  IS  sui;f)r.'stci)  'hat   the  liluTati.m 

(l,j>     ,..,.^.     ,.!•     .^..\\.^     ...      ,-..   . 

water. 


ti.'.'  a. 'ill   hy  hydrolyis  in 
iL-Kis  iiiay  i,ui.-,c   iiicir  n.'ijaiive   .ift-.-t   .m 


-1  KKACK    TKN.-ION     \M)    SALTS    IN    SOUTIOX 


l.")7 


All  acids  lower  surface  tension,  and  in  tiie  ease  of  the  laltv  a.-ids 
experiments  have  shown  that  the  louvrin;,'  is  proportional  "to  the 
carbon  content  of  the  acid. 

It   is  sufTir-'strd  in  th.-s..  researches  that  tlie  surface  tension  of  a 


o    s   /o   /s  20  as  30  S5  ^h>  ^S  So  SS 

Fio.  31. 


solution  of  two  salts  one  of  wiiich  raises  the  surface  tensi..n  and  the 
other  lowers  it,  is  an  additive  property  of  the  two  solutions— provided 
no  chemical  reaction  takes  place  between  them,  and  the  values  of 
the  two  are  not  far  removed  from  the  value  of  water.  If  one  of  the 
solutes  causes  a  much  larger  etfect  than  the  other,  the  value  of 
the  mixture  lies  closer  to  the  one  with  the  greater  etTect. 

Kegarding  the  variation  of  surface  tension  with  temperature 
It  is  made  clear  that  surface  t<.nsioii  increa.ses  witii  decrea.se  in' 
teiuperaturr 

In  revi,  ,ng  the  subject  of  flotation  in  one  of  the  mining  journals 
alKint  tvr,  vars  ago,  a  leading  educator  made  the  statement  that 
heat  nicreas(?s  surface  tension.  Now  this  is  absolutely  erroneous  in 
ca.s<.  of  pure  water  and  it  is  not  likely  that  it  would  maintain  in 
any  cas<..  I  do  „„t  mention  this  in  a  fault-fin<ling  spirit,  but  to 
show  that  in  the  science  of  flotation  the  metallurgical  engineer  faces 
problems  in  [-.hysics  and  chemistry  that  aiv  ahsolnti>ly  n.,w  f-.  bin, 

In  the  work  in  th.-  chemical  j.mrnals  the  surface  tension  of  pure 
water  is  taken  as  71.0.}  dynes  per  cm.  at  .■!n^  09.;^.'}  at  40°,  and  68.46 


1;> 


TH»i   KLOTATIUN    I'UoCKSS 


at  i.>  .  While  IIo(,v,t;  u.s,.s  ,s1  with  a(.ol„^.i..s.  Again  Hoover  makes 
ji  sli,.  o„  pa-e  M  «h,..v  h,.  says  tlu.l  surfare  tension  of  water  has 
'•■•■-'  .  .■t.M'.niMed  to  In.  a  foree  of  SI  dynes  prr  s<,,ia,e  eentin.etre. 
Mere  he  has  eonfuse.l  snrfaee  tension  in  dynes  i.er  eenli.netr..  with 
Miilac-e  en.Tcry  .n  •>,-«  per  s.,,  en,."  Work  ,in  ergsi  is  the  a.t  „f 
I>n..l.u'ing  a  ehange  in  oj.position  to  a  foreo  (in  dynes,  that  resists 
tins  .-hati-e.  Now,  ^M-avity  fiives  to  a  -ram  a  veh.eitv  of  !IS()  en,  i.rr 
s.-on,l.  It  ,s  th.Tcfore  equal  to  !),sO  dynes.  Ifenee  if  one  frra.n  !,.■ 
I'tt-a  vertu-ally  one  ...ntinietre,  tiie  work  d.,ne  against  gravitv  is 
!'N>  er-s.  Hooks  on  j.hysi.'s  .hMHonstrate  that  surfare  tension  (dviies. 
per  u.ut-WKlth  IS  rninierirally  equal  to  surface  ener<rv  (crgsi  per 
"M.t-area,  We  should  therefore  sp.ak  of  smfare  t.ns'ion  in  dvnes 
!"■>•  ".■ntunetre,  and  snrfaee  energy  in  ergs  per  square  eentimetre. 

Ihe  ahove  figures  on  surfare  tension  and  surface  energy  ini"ht 
I'o  apphe.l  to  the  so-ealied  surface  tension  nietiiod  of  flotation  such 
as  the  Wood  machine,  wh,.re  the  ore  is  fed  drv  onto  the  surface  of 
water  and  at  one  place  at  least,  in  the  West,  wlu^re  the  wet  oiled  j.ulp 
is  spread  uimn  the  surface  of  water  in  a  spitzkasteii 

While  0.0724  gni.  (71.();{    :   f)81  ^  per  sq.  r>„.  represents  the  weiHit 

that  It  requires  to  just  break  the  surface  inemhrane  of  pure  wat^'er 

ll.rre  IS  anotlu.r  factor,  and  that  is  the  sixe  of  the  diniple   formed' 

lake   the  .^ase  of  galena.     The   huoyant   far,„rs  are   the   membrane 

and  the  water  displaced.     Taking  the  speeiiic  gravitv  of  galena  at 

'.5,    the   maximum   volume   of   a   dimple   mi    (mr   sipiare   centimetre 

woul-i:    be    0.00%  cr.    (0.0724   :    7.5,    or    a    displacement    equal    to 

O.OO.tG    gm.   water.     Adding  the   two   quotients  we    lind    that   0  0S2 

.  11.0724 +  0.00!I6)   gm.  galena  per  .sq.  cm.  would  just  break  fhivu-'h" 

This   IS    not    mathematically   correct,    but    a   clo.se    approximatioii-- 

sufficiently  ..los(>,t  becaus.'  we  do  not  know  the  volume  of  the  foreign 

water  attached  and  the  condition  of  the  water. 


VA  Pa.so.  Texas.  September  24, 


Will  H.  Coghill. 


t'Concentration  of  Ores  liy  Flotation,'  2nci  rijition 
tSee  page  348  of  this  l/ook. 


,-.;    I  '•'f-y'??:; 


AIK-KKOTH    FU)TATI<)N  If,") 


AIR-FROTH  FLOTATION 

(From  the  Mining  and  Scientific  Press  of  October  Hi,  1915) 
A  LuiAL   N'KJiSlON  ijy  Tilt;  TkcHNULOIIY  of  TUE  I'liOCKtS.S 

lllerewitii  we  give  ii  part  of  tlie  address  made  l)y  ilr.  Walter  A. 
Scott,  counsel  for  defendants  in  the  case  of  .Minerals  Separation  v. 
Miami  recently  tried  at  Wilmington,  Delaware.  We  give  this  not 
only  because  the  learned  gentleiiian  discusses  the  underlying 
principles  of  the  flotation  process  in  an  interesting  way  but  because 
the  (piestious  put  by  the  Judge  are  such  as  would  suggest  themselves 
to  other  persons  curious  to  understand  the  subject.  In  reading  this 
excerpt  from  the  court  proceeilings  o'lr  readers  must  not  forget  that 
It  is  an  <.,  paiir  statement,  putting  forth  the  technology  of  the  subject 
with  a  view  to  aiding  the  ease  for  the  defendant.  Mr.  Scott  assumes 
that  oil  is  necessary  to  tiotation  and  also  that  the  force  of  surface 
tension  bursts  the  bubbles.  Neither  of  these  assumptions  can  he 
taken  for  granted  in  a  seientilic  discussion  however  useful  they  may 
lie  in  a  lawyer's  brief. — Kdituk.] 

The  manifestation  of  the  force  of  sui  face  tension  is  a  phenomenon 
that  shows  itself  as  a  tendency  of  any  liquid  body— we  may  confine 
ourselves  to  a  liquid— to  assume  that  shape  in  which  it  has  th-  least 
surface.  It  is  a  well-known  fact  that  in  the  form  of  a  sphere  the 
ratio  of  surface  to  volume  is  at  the  minimum.  Therefore  we  can 
say  that  surface  tension  is  tliot  force  or  property  which  tends  to 
.•anse  a  body  of  li(iui(l  to  assume  the  splieiical  f.rm,  in  order  to 
make  its  surrounding  surface  as  small  as  possible. 

We  are  fa-  .  ..ar  with  manifestations  of  this  force;  wiien  a  drop 
of  water  falls  upon  a  hot  stove,  we  see  it  immediately  come  into  the 
form  of  a  little  sphere.  The  explanation  of  that  probably  is  that 
the  stove,  being  hot,  generates  a  little  steam  all  around  tne  particles, 
and  that  frees  it  from  '.nterference  by  other  forces,  so  that  it  assumes 
the  shape  which  surface  tension  tends  to  give  it. 

I  think  the  ordinary  shot-tower,  where  molten  lead  when  poured 
or  droppe.l  a.ssumes  the  spherical  form  of  shot  is  probably  another 
manifestation  of  surface  t.nsion.  The  lead,  in.stead  of  dropping  in 
a  formless  mass  as  it  presses  th-ough  the  air.  under  the  influence 
of  the  contractile  force  around  its  surface  is  drawn  iin  into  a 
spherical  body. 

Another  illustration  is  the  tendency  which  we  obse-ve  .vhon  water 


160 


TllK   FLOTATION    I'HOCESS 


IS  spillr.i,  ue  will  say,  upon  a  smoi.tli  smtaw  (,r  tal.lo  \\\nx-  it  not 
lor  swrla...  tension  ,t  uoiil.l  .snr.a.l  out  in  ai,  inlin.tdv  thin  lavor- 
gravity  would  tend  to  pull  it  down  tlat.  But  surface  tension  ..mses 
It  to  assume  the  lonu  of  a  littl.-  l,ulf:e  of  water  .,n  the  tahle.  Vis,.„sitv 
01  the  water  ].rohahly  also  plays  a  part  in  that.  It  is  diilieult  U> 
.iKsentangle  all  of  these  eaus^-s.  Hut  surfaee  tension  surelv  ,s  one 
ot  the  torees  to  enter  into  that  eli'eet. 

Now,  tliis  surface  tension  exists  not  only  at  the  free  air-surfaee 
(lor  instance,  the  surface  of  the  water  in  this  glass,  hut  it  exists 
at  every  point  where  there  is  a  change  of  nidiuni,  that  is  where 
tlie  water  encounters  another  suhstance.  Surface  tension  h.re  is 
along  the  uater  surface,  the  air  surfac...  hut  that  surface  tension 
e.xists  clear  around  the  inner  surfa.v  of  ti,e  gla.ss  and  at  the  hottoni 
ol  the  glass;  it  luus  tl,e  sa.ue  rehition  to  the  water  around  the  glass 
and  at  the  bottom  of  the  f;lass  a.s  next  the  atmosphere  above  So 
this  surface  tension  exerts  itself  about  <he  entire  surface  of  a  bndv 
ol  liquid,  tending  to  draw  it  into  a  spherical  form. 

As  w   observe   a   bubble— for  instance,   a  soap-l)ubble— th,    idea 
that  we  are  apt  to  have  is  that  the  bubble  bursts  from  an  interior 
toree;  that  :s,  that  it  explodes.     We  are  accustomed  to  that  thought 
Ml   connection   witl    any  explosion  or  bursting.      I    apprehend   from 
the  testimony  of   these  experts  that  a  lessening  of  this  contractile 
force,  or  the  surfaee  tension,  tends  to  permanency  of  a  froth;  from 
tliat  fact   I   apprehend  that   the  force  -ausing  a  bubble  to  burst    is 
not  an  expansive  force  from  the  inside,  but  that  it  is  due  to  surface 
tension,  if  the  surface  tension  is  strong  enough.    For  instance,  imagine 
a  soap-bubble,  we  will  say,  three  inches  in  diameter.     It  is  surrou.uled 
by  a  very  thin  tilm  of  water  contaminated  or  modified  bv  ,soap      Tiie 
amount  of  water  in  that  tilm  whieh  surrounds  the  air  inside  of  the 
Inibble  is.  as  we  may  well  imagine,  very  small.     The  ordiiiarv  soap- 
bubble    bursting   upon    this   piece   of   paper   would    hardly    I.mvc    a 
visd.Ie  sign  of  water.     Now,  as  that  bubble  exists  a.s  a  bubble  tiie 
siiitacc  of  that  very  small  ammuit  of  wat.T  is  verv  large      If  is  the 
entir..  outer  surface  of   that   bubble   and   the   entire   inner   surface 
wliere  the  tilm  comes  in  contact  with  the  exteii..,-  air  ami  where  i* 
comes  in  contact  on  th.'  inside  with  the  encloseri  air.     Now    -,s-,.r  th-t 
i-umen.se   surface,    for  it    is  truly   immense    in   consideration   of   the 
small  amount  of  water,  there  is  this  contractile  force,  as  if  anmiid 
the  Imbble  there  were  stretched  a  sheet  of  rubber  constantly  drawing 
i.T.vard  to  rnake  tbal  buobie  smaiier.  and  iiie  effort  of  that  force  of 
surface   tension   to  reduce   the  area   of  the   water   forming  the   film 


AIR-FROTII    FLOTATION 


ICl 


HiL' 


Tin;    ll,ilT\-|[uN     I'KoCKf 


o  the  buhbks  suuply  pulls  it  i„,  bursts  it,  reduces  it  „,  a  drop 
"'",..  has  ,1,..  ,„„.i„una  of  surfa,.,..  So  I  Hppn.h..nd  that  th.  re.uv,,, 
<■'<•  'Hibbes  ,u  th...se  froths  In.rst  is  ou  a,..-„UMt  of  that  shriMkin,^ 
'"ward  that  lendoney  of  .surface  ten.sio,.  „,  gatlicr  the  water  into 
the  smallest  possilile  compass. 

The  e.xper.s  who  hav,.  te.stified  in  tliis  ca.se  say   .and   tl,e,r  views 
are  in  harmony  with  the  literature  o„  ,he  subjec,  ,  ,hat  any  substance 
Much  tends    ..lower  ..r  les.sen  the  .surface  tension  of  water  tends  to 
make  ,he   bubhl,.s  or  the  froth   more  persi.stent   „r  ,,ermanent;  an.i 
M,  view  of  what  [  have  said.  I  think  the  rea.son  whv  tlies,.  m.xiifvin.^ 
.■;gen  s  which   lower  the  sarfaee  tension  .,f  uater  also  tend  to  n'lake 
iie    troth    more   p,.rmanr„t    is   elear.      In    the   ...se   „f   pure   water 
liavm^r  a   surface   fusmn    whi,.),    I   think   is--wdl.    it    is  arbitrarilv 
represented  by  s.m,..  nun...ral-we  ean  say  1.     It  makes  no  differen,.," 
Now,  that   force  of  surfaee  fusion  in  clear  water  is  strong  enough' 
1"   iH.rst   these   hubbh.s.      It   pulls  in   an.l   bursts  th.m.      Hut   if   the 
waf.r  IS  tuoditied  by  s<„Me  agent,  su.-h   as  an   oU   in  emuhsion    or  a 
soluble  substance,  such  as  phenol  or  ..resol.  that  ..ontra..tiIc  drawing-iu 
force  IS  lessened,  and  therefore  the  bubble  has  greater  long..vitv   can 
-x.st  longer,  because  there  is  not  this  ...nstant  pulling  i„.     Ho.'while 
tins  surface  tension   manifests  it.self  in   various  wavs  and  has  been 
nlil.x-.l  ,n  various  ways,  so  far  as  this  bubble  flotation  or  froth  flota- 
■""  -s  .•..n..erne.l,  J  think  it  is  ch.ar  why  a  h.wering  of  that  surface 
tension   ten.is  to  permit   a  bubble  to  exist   longer.     And  all  n{  the 
experts  in   this  case  are  in  perfect  agrcmient  that  an  insoluble  oil 
"Hx.Hl  up,  or  emulsified.  lowers  the  surface  tension  in  procisoiv  the 
same  way  that  a  dis.solved  substance  does. 

The  phenomenon  of  the  flotation  of  .small  part,.  Ics  upon  the  surface 
of  water,  as  upon  the  surface  of  water  in  that  glns,s.  has  been  referr.'d 
to  as  sur.ace  t.'n.sion  flotation  or  skin  flotation.  That  is  a  matter  ..f 
arbitrary  nomenclature.  Th..  sur-ue  tension  effect  does  not  ,.nt..r 
into  that  effect  any  m.uv  than  ii  .Iocs  in  bubble  flotation  This 
stretched  membra,,,.,  as  we  pi,.ture  it.  surrounding  a  body  of  liquid 
ami  tending  to  .iraw  it  into  a  small  compass,  also  luis  the  propertv 
of  supporting  a  small  parth^le  upon  the  upper  surface  of  a  bod'v 
ot  water,  but  the  name  "surface  tension'  should  not  properlv  be 
restricted  to  that  kind  of  a  flotation,  b.^cause  the  surface  tension 
phenomena  enter  into  all  flotations,  and  it  is  the  lowering  of  that 
surface  tension  that  lea.ls  to  the  formation  of  the.se  froths  which 
iinve  hiDir  or  ie.ss  j)ermaneiii'V. 


.-C.'::-'  %•■'  ::-=?-' 


■a 


.MF{-KK()TII     I'l.dTATKiN 


IH.i 


K^si.ks  these  vari.u.s  ,,ri,.r  art  pat.Tits  an.l  puhli.-ati.ms  that  1 
have  referred  to,  in  whi.h  the  h.wering  of  surfa.v  fushm  is  utilixo.l 
or  tlie  purpose  of  giving  permanency  to  a  frotli  or  a  huhlWe  we 
have  other  patent.s.  I  believe  owned  by  the  ..oniplainants  in  this  eas.> 
patents  issue.l  to  seientifie  men,  teohnieal  n.en.  the  offieials  eonneeted 
with  these  eompanies.  in  whieh  Hey  also  explain  the  use  of  hoth 
soh.hle  and  u.soluhle  reagents  l„r  Ih..  purpose  of  eontributing 
etTieieney  to  a  l)ubble  or  froth  proces,s. 

Notable  among  tliose  is  patent  78,S.247.  wiiieh  is  in  evidenee 
Patent  7S8.247  w.s  grante.l  to  Cattern.ole,  Sulman,  an.l  I'ieard 
Sulman  and  Pieard  are  two  „f  tlie  grantees  of  the  patent  in  suit' 
Sow,  in  this  process-- 

TiiE  Coi-KT  (interposing)  :  What  is  the  date  of  that  patent? 
Mr.  Scott:     The  date  of  the  grant  was  April  2r..  1!)05-  the  diile 
ot  the  application  was  March  2f».  1004.     In  their  statement  of  inven- 
tion  in  pat-ent  788,247  tiiey  say: 

"Our  process  has  for  its  object  the  separation  of  minerals  from 
sdicious  or  earthy   matters  of  ores  by   nleans  of  soaps  Tr  simil.  • 

xhihr.  -^  "'"^-  ''  '^f I><;"^^«:'t  "P"»  the  superior  physical  attraeti^ 
exhibi  e.I  by  minerals  for  fatty  or  resin  acids,  or  for  certain  othS 
annnatie  denvates,  such  as  phenols,  cresois,  etc.,  which  form  sol u We 
salts  or  compounds  with  alkaline  hydrates."  soiunie 

Then  upon  tlie  first  page  of  that  same  patent  they  state: 

"The  mineral  particles  now  attached  to  or  more  or  less  coated  or 
enclosed  by  films  of  fatty  or  resin  acids  and  the  like,  arc  eapaldo  of 
being  separated  from  the  gangue  or  earthy  parti des  by  Various 
methc  Is  depending  upon  this  altered  phv.sical  eondi  fon  For 
example   the  coated  .nineral  particles  may  he  removed  by  generating 

foThe'fattv  or  '"  "-f  '"'■''"■"'  "'"■',■''  P-t-erentially  attach  ES v  ! 
to  the  fatty  or  si.nilar  acid  coate.l  particles  and  raise  them  to  the 
surtace  of  ,he  pulp,  whence  they  may  be  removed  by  skimming  ol- 

There  is  a  clear  statement  of  the  use  of  soluble  agents,  the  verv 
soluble  agents  uhich  are  mentioned  in  the  patents  here  in  suit  with 
their  us...  in  connection  with  gases  for  raising  them  to  the  surface 
and  the  only  way  in  which  a  gas  can  function  is  as  a  bubble  a.id 
this  effect  of  lowering  the  surface  tension  was  there  brought  about 
by  the  same  substances  which  are  in  use  today. 

In  patent  793. S08  uliieli   ia  t>>„  ,.„<„..♦  ,i:„",i._:..  „  ,,  „  . 

spiral  coil  that  we  have  had  so  much  discussion  about,  the  patentees 
state : 

"The  present  invention  relates  to  the  concentration  of  ores  by 


Kil 


■INK    hlDTATlilN     lltu(l>.'- 


M|>ar,-,ii,,n  ->l  Ih.;  in,.t;illitVn.i.s  .•..nslitiimts  .-n,,!  -nipliitr.  rnr\,uu 
Nulplnir  Mild  tl„.  lik,..  fn,i,i  thr  '^nw^ur.  I,v  „„,,„-.  „f  „ils  .-n,,.,.  tiir' 
"I-  Miiy  Mimlar  siihst.-in.-r  uln.li  l,;i.  ,-,  ,,n.r.. ivnti,-,!  Mtlinitv  i,,,-  i,i,.|iil' 
liti'i'oiis  iii.'ittcT  liver  ^'iiiii.nic." 

''"'"■   •■"'  ""•'■'■   iiirnli,,n,d    is  f   111,,   sul.sliiiirfs   in    ilsr   tndav 

<'(ml-tar  is  tlu'  pnii.ipal  sniuv...  I  think,  of  ph.-iinl  aii.l  .•.vs„l,  aii',1 
Jt   IS  us.mI  in  a  rni,!..  stale  in   flotation  .operations.      I   Ijiink  it   is  one 


N.    7:3.303 


H    I.  SULMA.N  i  H.  r.  KlhKFATRlCK-PICA.RD 

ORE  CO.SCL.STRATION. 

irfLlr*Tlrl  riiiD  o.'i  ^    it ,, 


P.ME.vrrD  .lUI.Y  4,  l''i)i 


1SBEET1    5wrr 


I'll-..    33.      MiK   vy 


' • ' :  •*,/ 

HI  (in  VTHl    (  (>ir     r.VTENT. 


M2¥'-'M,^;^m^: 


;y^\ 


<*• 


si-.%-%'!''C!iix'-  'X, 


mm 


liiiiiai 


AlK-KHUIll    Kl,()T\TION 


165 


of  the  sulistaiiws  whifli  tlie  misw..rs  to  tlie  interrogatories  say  lias  been 
used  l.y  the  Miami  coMipaiiy.  It  is  partially  soluble  and'  partiallv 
insoluble.  If  is  a  mixture.  And  then  this  patent,  after  naming  these 
substances,  oil.  grea.se.  insoluble  substances,  and  then  mentioriinfr  in 
the  .same  breath  tar.  whieh  is  partially  soluble  an.)  partiallv  insoluble, 
the  same  as  is  the  frothintr  agent  used  at  Miami,  after  e.xp'laining  the 
use  of  tliesi'  substani'i'S  goes  on  to  say: 

••According  to  one  method  of  carrying  out  our  invention  suitably 
.■rushed  ore  is  snspende.l  in  uater.  To  this  suspen.sio,,  a  proportio;, 
<.l  >n\.  grease,  or  tar  (hereinafter  referred  to  as  'oil'i  is  adde.l  an.l 
m.iy  mixeii  \vith  the  mass  by  any  suitable  means  in  .|uantilv  insuf- 
ticient  to  raise  the  oil  minenil  by  virtu,,  of  the  flotation  power  of 
!<■  0,1  alone.  .\  suitable  gas  is  now  geiierate.l  in  or  introduced  into 
ttie  •Kixturc  such  as  air,  carbonic  aeid  gas,  siilphureted  hvd-o-ei, 
or  the  like.  .         ^      . 

Now  here  again  we  have  a  process  in  which  a  .soluble  agent  is 
use.l.  Tar  is  not  completely  soluble,  but  the  complainant  has  taken 
the  position,  which  I  will  accept  for  the  purpose  of  argument  at 
present,  that  if  any  constituent  of  a  substance  is  soluble,  then  the 
substance  is  a  soluble  agent  under  the  second  and  third  patents  in 
suit.  Accepting,  for  the  sake  of  argument,  this  construction  of 
these  patents,  we  have  here  disclosed,  down  to  the  minutest  detail, 
every  operation  that  is  performed  at  Miami.  We  have  tar,  a  mixture 
of  soluble  and  insoluble  iiirents;  we  have  the  admixture  of  that 
substance  with  the  pulp;  we  have  the  introduction  of  that  substan.-e 
into  a  ves.s,'l  provided  at  the  bottom  with  means  for  the  admission 
of  air;  that  means  being  this  perforated  spiral  coil. 

2  p.  III.    Same  da.v. 

Mk.  Scott:  If  the  Court  plea.se.  just  l>efore  the  recess  I  was 
spi  aking  of  the  spiral  coil-pipe  machine,  the  perforated  spiral,  and 
had  stated  that  this  process  wa.s  identical  with  the  operations  at 
-Miami.  In  fact.  I  think  it  will  1...  .lillicult  for  anyone  to  conceive 
of  any  different  action  on  the  part  of  air  bubbles  es<^aping  through 
fine  holes  in  a  metal  pipe  or  a  sheet  of  metal,  and  the  same  bubbles 
escaping  through  similar  holes  in  a  canvas  bottom.  I  do  not  think 
the  thing  needs  any  argument,  the  two  proces.ses  are  absolutelv 
identical. 

An  attempt  has  be.m  made  to  establish  the  appearance  of  identitv 
'■'"■    -'^i^---'  •''•i-isa  o!   :;iir)!,i,.s  Viimii   resiiiis  from  tiie  -\liami 
operation  and  from  the  patent  793,808.  and  the  persistent  froth  tb;it 
results  from  the  violent  agitation  of  tlie  patents  in  suit. 


,  „  *^-.^^^^:'mm^^^mm^ 


1(16 


TIIK    H.OTATKIN    runCF> 


Now  certuiiily  to  the  i-ye  there  is  no  idiiitity  whatever.  And 
t;oint?  I'uitlier,  looking'  to  liie  real  essenee  of  tlie  two  ojifnitions,  we 
tiud  as  tjreat  a  distinction  as  tliere  is  in  the  a])iiearaiice.  The  agita- 
tion frotii  resnlts  from  violent  agitation  of  tin'  pnlp,  heatins,'  the 
air  into  very  fim'  partiiles  and  then  hrin>,'iMf;  the  li(inid  to  rest;  as 
the  (oiiit  lias  s<'en  iiere  in  eonrt,  wlien  tiie  atjitatiiifj  niechanisni 
\\as  stoj)ped,  there  arises  tliis  pei-sistent  froth  which  hists  for  days. 
Kvcn  wlien  shaken  in  a  holth-  in  aii'onhincc  with  the  dirc'tions  of 
the  California  Teehnieal  Jonrnal*.  we  sliowed  the  Court  a  froth  that 
had  stood  f<ir  some  two  weeks,  I  think  .Mr.  Dosenhaeh  testified.  That 
frotli  was  so  stronf?  that  it  ivinained  as  a  hridsfe  across  the  hottle, 
even  after  the  water  had  evaporated  out  from  heneath  it.  I  think 
that  matter  was  called  to  the  attention  of  the  Court,  that  the  stoppi^r 
had  heen  left  out,  an<i  that  frotli  wa.s  so  stronpr  that  it  simply 
adhered  to  the  sides  of  the  liottle.  and  hridfred  ai'ross  the  hottle 
without  any  support  whatever  from  lielow.  That  is  eharacteristie 
of  all  these  froths  that  are  formed  hy  this  violent  agitation. 

N'ow  contra-stinsr  with  that  we  have  what  was  exhibited  to 
the  Court  in  nuuiy  experiments  with  the  canvas-liottom  machine, 
our  Exhibit  f):!,  and  in  tii.-  ])erforated  spiral-pipe  iriachine,  our 
Kxhihit  52. 

The  tirst  difference  that  strikes  one  is  that  in  this  agitation  proces.s 
the  liquid  must  he  brought  to  rest  before  the  froth  will  form.  Tiie 
froHi  will  not  form  in  the  presence  of  and  simultaneously  with  that 
violent  ajritation.  The  afritating  mechanism  either  must  be  stop|)e(l, 
or  the  li(iuid  must  be  conducted  into  a  side  ves.sel  where  it  will  be 
<|uiet.  As  it  was  exhibited  in  court,  the  apitatinpr  mechanism  was 
stopped,  that  t)einp  merely  for  convenience  in  demonstration.  Roth 
complainant  and  defendant  did  it  in  that  manner.  Of  course,  that 
Would  make  the  operation  intermittent  if  it  was  applied  in  practice. 
It  would  simply  be  agitated,  and  stop,  and  take  off  some  froth,  and 
then  take  more  material,  and  agitate  again.  As  I  think  the  Court 
is  informed,  in  practice  the  pulp  flows  in  a  continuous  stream  through 
these  agitating  vessels  and  then  into  quiet  ves.scls  where  there  is  no 
agitator,  ves.sels  called  'spitzkasten,'  and  the  current  as  it  flows 
along  is  so  slow  and  gentle  that  the  froth  rises  in  these  quiet  spitz- 
kasten after  having  been  previously  agitated  in  the  ad.joining  agita- 
tion vessel.    And  that  is  a  sine  qua  tion  of  this  agitation  process:  that 

•  TThr  Cilifo^Hi-a  ./'*t^*"»<2?  of  Tcchtioloou.    Mr.  Soott  refers  to  the  n.rt!r!e  b.v 
the  three  students  abstracted  in  our  issue  of  Jufy  31.  1915, — Emtob.I 


AlEM-Kolll    Kl.ol' \  lluS  llii 

till-  pulp  Ik  sul).i('<'t('il  lirst  to  violrni  iiKitutioti  and  Ihi'ii  \>ti  hrouKht  h> 
rt'8t  I'or  this  CDlicroiit  frotli  to  rise. 

Now,  it  is  tMiually  of  lliu  <  ssoiu'C  ami  vital  to  the  process  carried 
on  at  Miami  that  just  tiie  opposite  conditions  i)rcvail.  In  the  process 
as  carried  on  at  .Miami  the  bubbles  which  carry  the  metal  concentrate 
to  the  surface  can  ris*;  and  can  exist  only  in  the  presence  of  these 

H«.  835,120.  PATENTED  NOV.  6,  1906 

H.  L.  SOLMAN,  H.  F.  KIRKPATRICK-PICARD  &  J.  BALLOT. 

OHE  CONCENTRATION. 

H-rLIOlTlOB  FiLCD  mT  »    l»'is 

I •lECTi  aiEtr  1 


7K  <?V'4yty. 


FlO.  34.       niAORAM  .XCCOMPAiNYINO  THE  MINKRAtS  8EPABATI0N  BASIC  PATENT. 


^m^a^mmSm 


KW 


TIIK    KI-OTATION     I'KOCKSS 


" "!'"«  •stii'iiins  (if  air  from  tlio  hottoiti  (if  Uic  vcs.s.1.     Th,.  .(.m- 

lilaiiiiiiil  has  (•(Kitfinlcd  that  the  iiicrt'  >?t'iitlf  (■iitrancc  of  tlicsc  IiuIjIiIcs 
at  till  Ii()lt4iiii  (if  the  vcsNcI  is  the  (■(iiiivaleiit  of  till'  violent  ntritaiKiii 
whifh  forms  a  vital  and  osseiitial  element  in  the  i)roee88  of  the 
patents  in  suit. 

There  a^rain  to  the  eye  there  is  no  similarity  and  no  .(juivaleney. 
In  the  agitation-froth  pnicess  of  the  patents  in  suit  and  they  are 
all  alike  in  the  meehatiieal  frcntment  of  the  pulp  liy  as;itatioii~-\ve 
have  a  mass  of  water  that  is  beaten  into  a  perfect  vortex  or  maelstrom, 
as  violent  a  movement  as  we  eari  (•(ineeivc  of;  whereas  in  the  .Miami 
process  where  the  air  is  admitted  tlirou^'li  a  permealile  liottom.  we 
have  no  more  agitation  than  one  would  oliserve  in  a  glass  of  cliar<r.-d 
lupior,  soda  water,  or  ehami)agne.  There  are  simjily  the  rising 
hulililes  coming  through  the  liquid.     So  far  there  is  no  suiiilarity. 

liook  at  the  principle  of  the  thing.  There  is  an  even  greater 
ilissimilarity.  In  llie  lirst  place,  a.s  I  have  just  stated,  in  the  agitation- 
froth  process  the  froth  or  huhlilcs  can  rise  oidy  after  the  agitation 
has  stopped,  or  after  the  i)ulp  has  heeii  conducted  to  a  (|uiet  i>Iace 
away  from  the  agitating  ve.s.sel. 

In  the  Jliami  process  the  moment  the  influx  of  air  stop.s— and 
air  is  what  is  contended  to  he  the  equivalent  „f  the  a^ritation.  that 
is,  the  incoming  stream  of  air— the  minute  that  stops  in  the  Miami 
proce.s.s.  the  entire  body  of  bubbles  carrying  the  concentrate  collapses. 
and  I  think  your  Honor  has  a  vivid  impres.sion  of  that  demonstration 
in  which  Mr.  Ver.xa  and  .Mr.  Hunt  first  turned  on  the  .lir  in  that 
spiral-coil  machine,  and  in  the  canva.s-bottom  machine,  and  huilt  up 
this  ma.ss  of  bubbles,  and  then  suddenly  turned  the  air  ot^'.  whereupon 
this  all  dropped. 

Now,  looking  at  the  matter  of  equivalency,  it  seems  to  be  an 
impossible  construction  of  the  facts  aiul  law  to  urge  that  the  incoming 
air-streams  in  the  bottom  of  the  permeable-bottom  cell,  whether  it 
be  the  spiral  pipe  or  the  canvas  bottom,  is  the  equivalent  of  the 
agitation,  when  their  action  is  precisely  opjwsite  in  respect  to  the 
formation  of  the  froth.  In  one  case  the  froth  forms  only  when 
the  agitation  ceases.  In  the  other  the  floating  or  rising  bubbles  exist 
oidy  while  the  so-called  agitation  is  going  on.  The  principle  ,,f  the 
two  things  is  as  different  is  the  manifestation  of  that  principle.  The 
manifestation  ditTers  in  this  respect  that  I  have  pointed  out.  In 
one    the    froth    rises   when    the    agitation    stops.      In    the   other   the 

Now  as  to  the  principle.     The  two  processes  attack  the  iiroblem 


wmmm^.m^'rym'^^^t 


-^T". 


AlK-KK(fTll    FLOTATION 


lefi 


ill  i-i>iiii)ltt<ly  (lirtVreiit  ways.  In  the  aKita'ioii-froth  profcss  tlic 
thoujfht  is  so  to  treat  tiiis  pulp  by  violent  aRitatioii  that  a  froth  will 
form  :u)(l  exist  after  agitation,  that  froth  to  be  of  so  permanent  and 
lastin^r  •  ■  mracter  that  it  can  be  manipulated,  can  be  floated  or 
skimmed  .f,  as  the  Court  has  seen  witnesses  do  in  this  case.  The 
idfa  tlitTf  v.ns  by  this  agitation  to  effect  a  separation  more  or  less 
permanent  in'tween  the  (Jfangue  and  the  concentrate,  to  jtet  the  gangue 
at  the  bottom  and  the  coneentrate  at  the  top — to  stratify  them,  as 
it  were.  We  have  th'  wo  strata  with  an  intervening  stratum  of 
water.  And  then  to  take  off  that  froth  in  any  way  which  may  be 
convenient,  either  by  simply  flowing  off  or  by  skimming,  jus  has 
been  explained  by  complainants'  witnesses  in  that  instance  where 
they  had  a  revolving  paddle  something  after  the  fiushion  of  the 
stern-wheel  on  some  of  the  river-steamers.  That  paddle  would  revolve 
and  scrape  off  this  froth. 

In  the  Miami  proee.ss  the  mode  of  attack  upon  the  problem  is 
completely  different.  There  is  no  idea  in  the  Miami  process  of 
stratifying  these  materials  and  making  a  permanent  float,  which  can 
be  scraped  off  or  floated  off.  The  thought  there,  and  the  process  as 
actually  carried  out,  is  to  admit  at  the  bottom  of  the  vessel  containing 
the  pulp  with  the  agent  that  is  used,  a  stream  of  air  bubbles  which 
act.  as  Dr.  Liebmann  has  Siud,  simply  like  an  upcast.  These  air 
bubbles,  rising  by  the  force  of  gravity  through  the  water,  collect 
the  mineral  particles  by  refison  of  the  fact  that  they  do  collect  them. 
That  is  about  all  that  we  can  say,  that  the  mineral  particles  adhere 
to  these  bubbles  while  the  gangue  does  not. 

Then  the  bubbles  come  to  the  surface  of  the  water  and  break 
almost  instantly.  There  is  a  constant  succession  of  breaking  bubbles, 
but  the  influx  of  air  at  the  bottom  of  this  vessel  manufactures  the.se 
bubbles  at  a  slightly  more  rapid  rate  than  they  break,  and  for  that 
reason  the  upper  layer  of  bubbles  is  overflowed  from  the  top  of  the 
vessel  and  saved,  with  their  burden  of  mineral.  The  only  reason 
that  the  Miami  process  is  a  success,  or  that  the  process  of  patent 
793,808  is  a  success,  is  that  it  is  possible  by  these  rising  bubbles  to 
make  the  bubbles  a  little  faster  than  they  break.     If  they  broke  as 

Mr.  Scott  :    Up  to  the  top. 

The  Coikt  :    Up  to  the  surface,  or  above  the  surface? 

Mr.  Scott  :    Precisely. 

The  Court:  Now.  where  in  the  complainant's  process  does  the 
bubt>le  attach  itself  to  the  mineral — below  the  surface  or  above? 

Mr.  Scott  :    T  think  that  must  be  below  the  surface,  too. 


n1 

■TjT 


TUE    KI.OIATION    ntOCE.SS 


last  as  tlicy  were  iiiadr,  we  would  never  have  any  appreciable  aiiimint 
of  bulil'-s  on  toi>,  They  would  simply  break,  each  one  in  time  for 
the  next  one  to  eoiiie  uj) ;  but  as  it  is  there  is  a  small  interval  of 
time  before  they  Imak.  and  more  bubbles  are  being  formed  at  a 
rate  so  rapid  that  some  of  those  bubbles  arc  raised  to  the  top  and 
carried  over  the  top  before  they  liave  broken,  and  that  is  the  only 
reason  that  it  is  possible  to  concentrate  ores  in  that  way. 

The  frothing  i)roi-es,s,  on  the  other  h.and,  is  not  dependent  upon 
any  such  principle  at  all.  The  thing  is  simply  agitated  violently, 
and  when  the  agitation  stops,  this  froth  rises  and  floats  much  the 
same  as  a  board  would.  It  nuiy  not  be  as  long-lived  as  a  piece  of 
wood,  but  it  la-sts  for  weeks,  and  it  simply  rises  there  and  floats. 
Speaking  with  r  gard  to  the  purpose  of  concentration,  it  is 
permanent,  within  the  limitations  that  pernuinency  is  necessary  or 
desirable. 

Now  in  view 

THK  CoLUT:  Let  me  see  if  I  get  your  idea.  Do  you  draw  a 
distinction  between  a  process  which  results  in  the  formation  of  what 
is  termed  a  permanent  frotii,  and  a  process  in  which  the  bubbles  come 
up  in  rapid  succession,  but  not  in  such  quantities  or  in  such  close 
proximity  as  to  form  a  permanent  froth,  but  as  soon  as  they  get  to 
the  surface  tli.'y  float  away;  is  that  what  you  mean? 

Mr.  Scott  :  Tiiey  float  over,  if  we  get  them  over  before  th»y 
lireak.    Jt  is  a  kind  of  a  race. 

TuK  CorRT;  If  you  get  th<  m  over  before  they  break!  But 
suppose  they  break  before  you  get  them  over,  what  becomes  of  the 
iiuneral  ? 

Mii.  ScdTT:  Then,  as  is  shown  in  these  demonstrations,  if  they 
do  break,  the  mineral  drops,  and  it  \a  caught  by  the  bul)bles  below. 

TiiK  CofiiT :    And  brought  up  again? 

Mr.  Scott  :  Atid  brought  up  again.  The  'nubbles  must-  lie  brought 
up  fast  enough  st>  that  it  will  graduall;.  be  raised. 

Tin:  f'oiKT :     That  is,  above  the  surface, 

Mr.  Scott  :  Yes.  There  ii^'ist  be  new  bubbles  coming  fast  enough 
so  that  it  is  gradually  carried  up  over. 

TiiK  f'orRT:     And  they  float  off? 

Mr.  Scott  :    And  finally  float  off. 

TiiK  ('(HRT:  That  is  what  I  meant.  I  did  not  express  it  in  that 
way.  You  cxpres.sed  it  ii,  two  stages,  a  first  jna.ss  of  bubbles  and  a 
succeeding  mass  of  bubbles,  but  that  was  what  was  in  my  niiiul, 

Mr.  Scott  :     The  same  idea.  I  think. 


AIK-KKOTK    l-l.oTATInX 


The  Couut:     Tliat  tlicre  is  no  pcriuaiiciK'c ? 

Mi{.  Scott  :  No  permaiifiice  iu  the  Imlililc  process  at  Miami. 
Now,  if  the  Court  reiiiL'iiil)ci-s  the  mass  of  hulililes  was  probaJ)ly  about 
a  iiiL-lu's  liigh  ahove  the  water,  as  1  remeuibei. 

Mis.  Kionyon:     Ten  or  twelve  iiiohes  lii^'li. 

Mb.  Scott  :  Ten  or  twelve  inelios  hiph.  It  was  quite  hi5?li.  Now, 
if  a  partiele  should  be  allowed  to  drop  by  rea.son  of  the  bubble 
breaking,  it  ivould  be  caught  on  a  bubl)lc  below,  aiid  tlius  constantly 
raised  up  by  new  bul)bles  cominf,'  into  the  bottom,  so  that  it  is,  as 
you  might  say,  a  cas<;  of  stepping  back  an  inch  and  going  forward 
two  inches,  and  gradually  getting  over,  despite  the  breaking  of  tl'<> 
bubbles. 

The  term  'flotation'  .seems  inaeeurate  as  applied  to  this  Miami 
proces.s.  In  tb  agitation-froth  process,  after  the  agitation  is  stopped, 
this  froth  actually  does  float.  It  will  float  for  hours,  and  days,  and 
wwks,  and  stay  on  the  top  of  the  water;  but  in  the  Miami  proces.s, 
as  soon  as  the  incoming  current  of  air  stops,  everything  drops,  and 
we  have  the  clear  water-surface  on  the  top  of  the  cell.  Now,  that 
demonstrates  absolutely  that  that  mass  of  bubbles  several  inches 
deep,  which  we  .see  in  the  Miami  process  operation,  or  that  of  the 
patent  793,808,  is  not  really  floating,  [t  is  held  up  there  by  the 
current  of  air,  which  holds  it  in  place.  That  current  of  air  not  only 
manufactures  these  bubbles  so  fa.st  that  we  have  that  mass  of  bubbles 
there,  but  it  actually  holds  them  up  in  position,  and  the  minute  the  air 
is  turned  off  everything  drops.  The  mineral  goes  right  to  the  bottom, 
and  the  bulibles  break.  So  that  instead  of  a  floating  ma.ss  of 
••oncentrate,  it  seems  to  me  that  it  is  liest  described,  as  I  think  I  did 
once  before  in  opening  the  ca.se,  by  saying  that  this  Miami  operation 
io  similar  (o  these  devices  we  have  seen,  where  a  stream  of  air  is 
blown  out  of  a  pipe  and  a  ball  floats  above  it.  The  minute  the  stream 
of  air  is  turned  off  the  ball  drops.  In  pojndar  language,  we  may 
say  that  that  ball  is  floating  in  the  air.  but  obviously  that  is  a 
mi.snomer,  if  we  attach  any  e.xact  meaning  to  our  words. 

Now,  the  Miami  process  is  analogous  to  this  ball  held  up  on  that 
stream   of  air.     The  agitation-froth   process   is  the   ball   floating   i' 
the     water.     The    two     things    operate    upon     absolutely     differen* 
principles,  and  the  ditTerencc  is  so  great  that  it  cannot  escape  anyone's 
notice. 

Dr.  I.iebmann  has  characteri/c<l  this  Miami  cell,  or  Callow  cell, 
as  he  calls  it,  as  an  ui)ca.st,  and  the  f:gnr»  of  speech  is  very  happy. 
We   took   an  ordinary  upca.st  with   water,   such   as  that   which   was 


TIIK    ri,UTATIOV    PROCESS 


iisfil  for  separating  the  I'attrrmok'  granules;  and  the  Court  will 
well  rcnioinber  that  t}ie  mixture,  the  grajiules  and  gangue,  was 
liroiight  downward  into  a  pipe,  and  wat'-r  was  flowing  upward  ii.  the 
pipe.  ;ind  that  upwa.rd  stream  of  water  carried  otf  the  light  fading, 
and  tlie  heavy  granules  sank  to  the  bottom.  Now,  'upcast'  is  the 
term  that  is  ordinarily  used,  and  the  action  which  takes  place  iii  this 
Miami  process  is  alisulutely  analogous  to  that.  It  is  not  a  floating 
operation.  It  is  an  operation  in  which,  in  a  rising  current  of  air, 
t-'ravity  is  sti-irii;;  enough  to  pull  sonic  t)f  the  [larticlcs  down,  hut  'm' 
.".ther  particles  are  of  siich  gravity  and  shape  that  the  rising  ■•  niit 
of  air  carries  them  up  against  the  force  of  gravity. 

TiiK  CoruT :  Let  mc  ask  you.  where  is  the  gangue  separated  from 
the  metal? 

Mk.  Scott  : 

The  Court 

Mr.  Scott  : 


In  tiie  Miami  process? 
Yes. 
The  gangue  comes  out  at  the  bottom  and  the  mineral 
is  carried  over  the  top. 

The  Coikt:     Yes.     IIow  is  that  the  result  of  this  upcast? 
Of  air? 
What    is  it    that   separates   the   gangue    from   the 


Mr.  Scott- 

The  Coikt 
Iiarticlcs? 

Mr.  Scott  :  The  rationale  of  the  tlu'-.g  is  evidently  this:  We 
have  in  this  cell,  or  tank  with  the  porous  bottom,  water  carrying  in 
suspension  both  gangue  particles  and  mineral  particles,  and  the 
nii.xture  has  been  treated  witii  some  of  these  ag  ats — tar,  or  coal 
tar,  or  what  not — mixed  up  with  it.  In  the  firet  place,  those  air 
bubbles  attract  to  themselvi's  the  mineral  particles  and  do  not  attract 
the  ganiru(>  i)articlcs;  so  that  at  that  stage  of  tiie  operation  we  have 
in  the  water  a  series  of  bubbles  with  the  mineral  paiticles  sticking 
to  them  and  we  have  the  gangue  particles  free  in  the  water  itself. 
Now,  thos<^  bubbles  rise,  of  course,  by  gravity  and  carry  with  them 
those  nniieral  i)articles.  The  combination  of  the  nubble  and  the 
mineral  particle  is  together  lighter  than  water,  .so  it  goes  to  the  top. 

TiikCoikt:     I  understand. 

^1r.  Scott  :  And  the  gangue  particle  has  had  no  assistance  what- 
ever from  tlie  air.  It  is  still  heavier  than  water,  the  way  it  always 
was,  and  it  goes  to  the  bottom. 

The  Coi'RT :     I  understaml,  then,  that  i'    the  Miami  proees-s 
bubble  attaches  itself  to  the  mineral  beiow  the  surface. 

Mr,  Scott  :    Helow  the  s\irface,  yes. 

The  CdiKT:     Aik'  carries  the  mineral — 


AIK-KROTH    KI>()T.\TI()N 


173 


The  Court:     And  it  carries  it  up,  does  it? 

-Mk.  Scutt:     It  cairies  it  up  to  the  top. 

The  Court:  Is  it  not  pretty  much  a  question  of  froth,  rather 
tliau  of  concentration — tiie  difference  between  the  two  processes?  1 
understand  that  the  purpose  of  the  patents  is  to  eflfoct  not  a  frotli, 
hut  a  concentration. 

Mk.  Scott.    I'recisi-ly. 

The  Court:     A  separrtion? 

Mr.  Scott  :    Precisely. 

The  Coikt:  Now,  you  may  assume  tiuit  I  do  not  liiiow  anything 
about  this.  I  want  to  iiave  it  put  to  me  as  plainly  as  you  can  express 
yourself.  What  is  the  distinction  in  principli'  between  those  two 
processes?  You  have  explained  the  difference  in  point  of  actual 
o[)eiatioii.  \ow,  what  is  the  distinction  in  principle,  when  it  comes 
to  the  foniiulation  of  any  principle,  between  these  two  operations, 
as  bearnig  ui)on  the  (piestion  of  the  separation  and  saving  of  the 
metal  particles? 

Mk.  Scott  :  The  broad  principles  are  the  .same  in  lioth.  In  both 
we  lia.c  the  pulp,  consisting  of  ore  held  in  suspension  in  water.  In 
both  the  water  is  modified  to  lower  its  surface  tension.  In  both 
the  l)uoyancy  comes  from  air  bubbles.  The  difference  comes  after 
the  air  bul)l)i"s  have  attached  themselves  to  the  mineral  particles. 
In  the  afritation-frotii  p-.x'css  the  air  is  beaten  into  very  minute 
bubbles,  and  when  they  rise  with  these  mineral  particles  they  form 
this  permanent  froth.  The  j  crmanent  froth  is  then  floated  off  or 
skunmed  off.  Now,  in  the  Miami  process  there  is  no  beating  up  of 
tlie  licjuid.  of  the  pulp.  The  bubbles  are  larger  and  more  fragile, 
and  instead  of  forming  a  permanent  froth,  whicii  vill  float,  the  thing 
is  simply  pushed  off  by  the  current  of  air.  The  basic  principles  are 
the  .s;ime  in  both  of  them.  The  method  practised  at  Jliami  is  the 
older  of  tlie  method's.  It  is  the  method  of  the  patent  793,808,  with 
the  perforated  spiral  coil. 

Now,  speaking  so  far  as  patents  go,  departing  from  the  Court's 
<luestion  as  to  the  general  j)rineii)le  of  the  thing,  which  is  identical 
up  to  the  point  I  have  expiained — departing  from  broad  explanations 
and  approaching  it  from  the  patent  side  purely,  the  patents  in  suit 
must  neces-sarily,  if  they  have  any  validity  whatever,  be  restricted 
to  this  permanent  froth  formed  by  *his  mechanical  agitation,  or  they 
must  confessedly  be  invalid  by  'J  e  prior  existence  of  the  perforated 
coil-pipe  mncliiiie. 

The  Court:     Let  me  a.sk  you  another  question. 


174 


TIIK    KI.dTATION    I'R(I(Km 


Mk.  Scott  :     Certainly,  I  am  very  glad  to  have  you  do  so. 

Till-;  CoiuT:    Wlii'ii  was  the  ixTt'orati'd-coil  inachiiic  lirst  used.' 

JIk.  Scott  :    As  far  as  the  rcronl  in  tiiis  case  shows — 

TiiE  CoiitT:    I  iiuan  with  respci-t  to  tiic  tirst  patent  in  suit. 

Mi(.  SriiTT:  The  date  of  tlie  aj)i)lieution  was  ahout  a  eoujile  of 
years  before,  and  I  think  the  patent  was  <rranted  ahout  a  luontii 
before  the  ai)pliratioi;  in  this  eountry.  J  will  give  you  the  exaet 
date.! 

TiiK  CoriiT:    1  mean,  was  it  l)efore? 

AIk.  Scott  :    Oh,  absolutdy. 

TnK  CoruT:    H.^fore  the  tirst  i)atent  in  suit? 

Mr.  Scott :    Before  the  first  patent  in  suit. 

The  CoiUT:  Now,  let  me  ask  you.  what  were  the  ingivdients 
that  were  used,  and  what  proportions  were  used? 

Mu.  Scott  :  In  tliis  patrnt  the  ingredient.s— and.  of  rour.se.  in 
all  of  the.se— are  the  oro-])ulp  m  the  first  plaee.  the  water  and  the  ,„-e. 

Tin;  ColKT:     Ves. 

^fii.  Scott  :  .\n<i  the  ingredient.s  for  efTecting  l)ul.i)le  formation 
m  tiiis  i)atent  7!t;i.s08  are  oils,  grease  and  tar.  or  any  similar  .suhstanee. 
wliieli  has  a  i)referential  atlhnity  for  metalliferous  matter  over  iransrue. 

Tm:  Coiht:     And  in  what  firdpoi'tions? 

:Mh.  Scott  :  'i'iie  proportions  are  stated  in  the  patent  in  tiiis 
lan^'uairi — tliere  are  no  lifnires— in  line  8!t  of  the  tirst  pagi'  of  tiie 
patent  : 

"We  have  also  found  that  a  partiele  of  metalliferous  mineral,  if 
eoated  with  a  minute  film  of  oil.  grease  or  the  like*  *  •  •  •• 
And  so  forth.  Thai  expression,  "minute  film"  certainly  gives  us 
in(liiation  of  a  xi'vy  small  (piantity,  because  the  word  'film"  ..ithout 
any  (lualification  whatever,  conveys  to  the  mind  the  idea  of  a  \cry 
small  amount:  and  when  you  say  ■'a  minute  film"  we  are  getting 
about  the  strongest  ( .\i)res.sion  of  the  necessity  of  a  small  quantity 
tliat  words  can  convey. 

Theiv  is  one  other  jilace  in  this  patent  where  I  think  the  (|uantity 
is  similarly  cliaracferi/ed. 

Mr.  SiiKi{in.\.\:     At  till'  top  of  page  2. 

:\ln,  ScoiT:  "A  small  proportion  of  oil."  following  th(>  "minute 
film." 

t[lhr  roil-piiic  iiatcni  (No.  7n.'?.S0S  i  is  d.itPd  .Iiil.v  4.  190.->.  l)ut  tho  applica- 
tion was  filed  on  October  .■..  iW?,.  On  ttio  other  liiind  the  l)asic  agitation-froth 
patent  N.I.  .S.'!,'->.120  is  dated  November  fi,  WW,,  while  api)lication  for  it  was 
made  on  May  29.  190.').— Ethtor.] 


WHY    IH)    MINFJiAI.S    Kl,OAT^ 


175 


This  brings  'is,  of  course,  to  what  I  regard  as  the  only  real  ques- 
tion in  the  case,  and  that  is  as  to  wliether  there  is  any  distinction  in 
principle  between  the  frotii  wliich  is  formed  with  a  very  small  quantity 
of  oil  and  one  which  is  formed  with  a  larger  quantity;  in  other 
words,  whether  there  is  a  diflferenoe  between  an  air-froth  and  an 
oilfroth  or  emulsion.  The  first  patent  in  suit,  8.'jr},120.  states  'het  less 
than  1%  of  oil  is  us( d ;  and  then  in  describing  the  action  of  that  oil  it 
states  that  it  coats  the  mineral  particles.  Well,  they  cannot  he  coated 
otherwise  than  by  a  miimte  film.  The  descriptive  language  is  pre- 
cisely the  same,  and  then,  as  shown  by  the  demonstrations  in  this 
Court,  we  have  produced  the  same  result  ocidarly,  and  nietallurp 
ically.  with  these  large  quantities  of  oil  as  with  the  minute  i|uaiititv. 


WHY  DO  MINERALS  FLOAT? 

By  Olivek  C.  R.»lston 
(From  the  Mining  and  Scientific  Press  of  October  2;i,  1915 » 

*I  was  very  much  interested  in  reading  an  article  by  Charles  T. 
Durell,  ai-peariiig  in  the  Mining  and  Scientific  I'nss  of  September  18, 
under  the  caption  '  Why  Is  Flotation  ?'  However.  I  fiml  myself  unal)le 
to  agree  with  .Mr.  Durell'ti  line  of  argument,  and  for  the  following 
reasons : 

In  the  first  place  I  believe  that  Mr.  Durell  has  used  loosely  s<ime 
rather  obscure  scientific  terms  which  may  canst;  unnecessary  confusion 
to  anyone  not  thoroughly  familiar  with  the  physical  chemistry  in- 
volved. The  term  'na.seeiit  gas'  is  especially  ,  pen  to  criticism.  Doubt- 
less Mr.  Durell  means  the  dis-solved  gas  that  can  be  liberated  from  the 
water,  but  that  is  hardly  the  ordinary  sense  of  the  term,  and  many 
modern  physical  cheunsts  will  onject  lO  the  use  ot  the  word  'nascent' 
under  any  coii'litions  whatever,  or  even  r(  aise  to  recogniz"  it,  in  spite 
of  the  old  ideas  that  grew  up  around  it.  However,  it  may  be  that 
■na,scent'  is  a  good  term  to  use  here  in  a  figurative  sense.  Another 
term  used  by  Mr.  Durell  and  to  which  an  objection  might  i)e  raised 
is  the  word  'occlusion'  as  applied  to  the  gas<'S  hehl  by  minerals. 
Mineralogists  have  lont-  u.sed  this  term  rather  loosely,  but  Ttlr.  Durell 

»Coniinuniciited  by  n.  A.  Lyon,  nietallurKlst  in  chaie;?  of  t'tah  ?:xppr!- 
ment  Station,  U.  S.  Bureau  of  Mines  and  Department  of  Metallurgical 
Research  of  I'niversily  of  Ttah.  Salt  Lake  City,  Itah.  O.  C.  Ralston, 
as.si£tant  metallurgist. 


i7f; 


TllK    FLOTATION    TKOCKSS 


(lots  not  sciiii  to  liavi'  taken  it  up  in  tlu'  sii;nc  sense.  As  I  nndcrstand 
it.  tluTc  are  three  ways  otiier  than  in  visiliie  openings  l)y  which  gases 
i-aii  lie  iielii  in  solids;'  these  ai'e: 

I.  In  solid  solution,  in  the  sanii-  way  that  prases  lan  he  lield  in 
ii(iuid  .solutions. 

'2.  In  .surface  .idsorption,  where  the  layer  of  gas  iinniediatcdy  in 
i-ontaet  with  the  solid  is  found  to  he  more  or  less  tightly  iield  hy  some 
force  of  attraction,  unnamed,  and  is  hence  considerahly  compressed. 

;f.  In  occlude.l  form.  This  is  a  term  the  meaning  of  which  has 
l)een  much  disi)uted  ;  it  is  (d"ten  used  in  the  sense  of  one  or  the  other 
of  the  tenris  aliove  -lentioned.  Of  late  there  has  heen  a  tendency  to 
call  occluded  ga.s  any  gas  that  seemingly  is  held  in  some  manner  dif- 
ferent from  that  designated  l)y  either  of  tl tlier  two  tciins.  and  in 

a  manner  not  exactly  understood.  An  example  is  found  in  certain 
suhstanees  that  are  known  to  he  finely  porous  and  that  seem  to  hold 
ga.si'S  in  neither  solid  solution  nor  surface  adsorption.  Charcoal  is 
such  a  .suhstance.  I'o.ssihly  these  have  pores  of  su<'h  small  diameter 
that  they  are  of  the  sauu'  order  of  magiutude  as  the  thickness  of  tjie 
adsorl)ed  layer  of  gas,  .so  that  most  of  the  gas  nehl  in  them  is  present 
m  a  highly  compressed  condition.  Charcoal  ahsorhs  so  much  CO,, 
for  instance,  that  at  ordimiry  teini)eratures  the  volume  of  COn  lield 
is  enough  to  till  ilie  known  pore  space  at  a  pressure  suflfieient  to 
li(|ui fy  it.- 

There  doniitle.ss  are  very  tine  openings  in  our  crystalline  sulphides, 
and  they  admittedly  do  hohl  some  oechnh'd  gas.  l)ut  good  cases  of 
occlusion  have  heen  found  thus  far  only  in  a-norphous  suhstanees  like 
<'harcoal.  hair.  w(h)1.  glue,  meerschaum,  starch,  etc.  This  fact  tends 
to  ca.st  a  dotilil  upon  Mr.  Durell's  hypothesis  that  the  occluded  gas  in 
the  flotative  minerals  plays  an  active  |)art  in  the  attai'hment  of  gas 
liid)hles  to  the  surface  of  the  mineral. 

Another  i)hysieal  fact  that  easts  further  douht  on  this  hypothesis 
is  tiuit  oeeludcd  gases  (and  dis.s<ilved  gases  as  well  <  are  liherated  from 
the  suli.staiices  occluding  them  oidy  with  difiicultv;  the  hust  trai-es  of 
them  are  still  held  even  when  the  substance  is  placed  in  a  high  vacuum 
and  heated  to  a  consideiahle  degree.  It  is  as  though  the  molecules  of 
the  gas  were  diffusing  out  through  very  small  clogged  pores.  Ifow 
this  tightlv-held  gas  could  he  iilierated  fast  enough  to  compare  with 
the  exeeediiifiiy  short  time  -v  .icli  it  takes  to  jiceomi)lish  flotation  of  a 


tPhilosniihiidl  Mn!iii:iiu\  Vol.  XVIII.  pa^e  Olfi,  1909. 

-See  the  researrhps  of  Sir  .lames  newar  on  cliarroal.  inil)lishi-(i  iti  various 
volumea  of  Chemicr.l  News. 


WliV    W)    MINKKAI.S    KI-<).\T.' 


177 


sulphidf  pjirticlf,  is  dirtiiult  to  explain  jdiysiciiily.  .Mr.  Durcll  lias 
further  supposed  that  thiTc  is  an  osmotiu  tnivel  of  ions  from  tin-  water 
solution,  in  which  the  ore  pulp  is  made  up,  direetly  into  the  tine  open- 
iiijfs  of  the  mineral  partieles.  The  surface  of  the  particle  acts  as  a 
sei)tum  and  at  the  sjiine  time  the  molecules  of  the  gas  dilfus*'  out  and 
join  the  air  from  the  solution,  forming,'  a  liuhhle  that  floats  the  min- 
eral. At  the  present  time  I  cannot  see  my  way  to  accept  Mr.  Dnrell's 
supposition.  lirietly  .stated,  then,  Mr.  Durell's  hypothesis  is  that 
"nascent"  gius  from  tiie  water  and  "dissolved"  gas  from  the  solid 
meet  and  colh-ct  at  the  surface  of  the  solid  iintil  a  l)ubhle  large  enough 
to  lift  the  particle  is  formed,  while  the  purpose  of  an  oil  is  to  form 
a  i)ersi8tent  froth  so  that  the  particle  will  not  he  droppetl  back  into 
the  pulp.  I  am  of  the  opinion  that  all  the  plienomena  cited  by  Mr. 
Durell  constitute  no  proof  of  any  part  of  his  hyjxjthesis,  l)ut  only 
furnish  the  basis  for  an  inference  that  such  could  be  the  case.  Whether 
it  is  possible  to  get  flotation  from  water  containing  no  dis-solved  ga.ses 
and  with  minerals  tiiat  have  titen  treated  for  the  removal  of  their 
occluded  gases,  no  one  knows.  Possibly  Mr.  Uurell  is  right  when  he 
says  that  "this  phenomenon  is  worthy  of  invistigation,"  but,  on  the 
other  hand.  I  believe  tiiat  flotation  can  be  explained  more  satisfactorily 
than  t)y  the  conjecture  that  well  crystallized  minerals,  such  as  the 
metallic  sulphides,  contain  important  amounts  of  either  occluded  or 
dis,solved  giise.s,  and  that  they  contain  these  giuses  in  any  greater 
amount  than  do  the  e(|ually  well  crystallized  gangue-minerals,  such 
as  (|uartz  and  feldspar.  That  surface  films  of  adsorbed  gas  or  air 
exist  and  may  be  of  great  importance,  I  firmly  believe,  but  there  is 
little  evidence  of  any  great  difference  in  the  amount  of  this  gas  on 
gangue  and  on  tlotativc  minerals. 

As  I  understand  Mr.  Durell,  the  sole  u.se  of  the  oil  in  froth-flota- 
tion is  the  formation  of  a  tougher  liquid  film  around  the  bubbles  of 
air,  so  that  the  resulting  froth  is  more  persistent.  Mr.  Kickard"  has 
Iiointed  out  that  various  writers  have  continually  made  the  statement 
that  the  surface  tension  of  water  is  iiunnsal  oy  the  addition  of  the 
oil,  while  as  a  matter  of  fact  it  is  (hrnasid.  This  fact  J[r.  Durcll 
acknowledges,  and  yet  he  states  that  because  the  surface  tension  of 
the  water  is  decrcas<'d,  the  tendency  to  float  is  likewise  decreased.  Tie 
implies  that  the  rea.son  is  because  tne  bubbles  burst  moro  easily.  This 
seems  .strange,  but  in  the  abscnci>  of  further  data  we  can  let  it  |>ass. 
My  main  comment  is  that  while  ^fr.  T)urcll  believes  that  the  only 
function  of  oil  is  the  toughening  of  the  surface  film,  we  are  not  sure 


■iM.  ,<  S.  P..  Sept.  II,  191.-),  pp.pe  S.SH. 


l7^ 


rilK    KI-OTATIDN     I'KOIKSS 


thai  su.-h  is  ilu.  nisr.  Mis  liypotlic.sis  iiLcmt  ••na.sr,.Mt "  Kas  and 
'•"'■.•liidcd"  tras  decs  iiol  iv(|iiir."  111,.  |)nsri„'(.  of  oil ;  l„.,i,-,.  lie  lias  had 
to  r\|)hiiii  the  lis.'  of  oil  op  aliaiidori  the  liy|iotiicsis. 

Althoujrh  I  .■oiisidrr  th.it  .Mr.  Dinvll  should  1.,.  api)laud.Ml  for  his 

foiirat;.'  in  piitliiii,'  forwanl  a  hypothesis  coi riiiiip  a  siihj<.ct   that 

has  hocii  of  so  enipiriral  a  iiatuiv  up  to  dale,  n.^wrtheless  I  have  felt 
the  ueeessity  for  .■hallei.-iiifr  .Mr.  Durell's  hypothesis  fuid  of  taking 
the  liherty  of  advain-iug  what  weiiis  to  me  to  he  a  better  one. 

There  are  two  siicii  hyix.tlies-s  wh'eli  seem  to  he  e(|ually  possible 
and  it  is  not  .-rlain  l.iit  that  th.'  two  simply  eover  parts  of  a  frreater 
fact.  One  liypotliesis  can  he  stated  in  terms  of  the  iiiter-faeial  ten- 
sions involve<l.  and  the  other  in  terms  ,.f  the  elertrie  .'harpes  residing 
on  .suspendi'd  particles. 

Tile    lirst    hypothesis   is   l.ase.l   on   son;e   academic    work   done   l.y 
Ilcniders.*    He  hjused  his  work  on  some  e-iuations  that  Clerk  .Ma.xwell' 
ha.l  derived  from  fundamental  tliermo-dynaniie  law.s,  leadinfir  np  to  a 
certain  .set  of  inef|iialities  hetwe.-n  inler-faeial  ten.sions  of  the  phases 
inv(,.  ed.     I{y  •inter-facial  tension'  I  mean  the  state  of  .strain  existing 
at  the  zone  of  meeting'  of  any  two  dis.similar  pha.ses.     The  .surface  o'f 
water  i(    contact  with  air  is  under  a  strain  which  we  call  'surface 
tension,'  .so  that  this  su.-faee  acts  like  a  tisjlitly-stretclied  ruhher  mem- 
lirane.    Likewise  the  inter-faee  between  a  solid  and  water  and  betweei 
a  .solid  and  air  or  between  e-l  i.nd  water  is  under  a  similar  strain. 
Allusion  lias  been  made  already  to  the  surface  adsorption  of  air  on 
solids.    The  inter- •'aeial  tensions  of  many  pairs  of  licpiids  are  known, 
as  well  as  the  surface  tensions  of  all  manner  of  liquids  in  contact  with 
all  manner  of  ga.se.s.     However,  the  intor-faeial  tensions  of  solids  in 
contact  with  liquid.s  have  nev    •  been  studied  thorougbly  on  account  of 
the  difiiciilty  of  getting  measurements  that  mean  anything.    Keinders 
<leduced  the  following  ineriUHlities  as  applying  to  the  ca.se  where  a 
powder,  or  the  particles  of  a  colloid,  is  su  ;pended  in  a  l.qnid  to  which 
IS  added  a  second  liquid  that  is  immiscible  with  the  first.     Let  us 
assume  that  the  first  liqui<l  is  water  and  the  seecmd  oil,  then  expres.sing 
the  inter-facial  tension  between  the  solid  and  water  us  T,,,,,  the 
tension  betw.-en  water  and  oil  as  T,„.„..  and  the  tension  between  the 
solid  and  oil  as  T,,.„,,  Reinders  stated  tli    ,: 

I'   r,..o,  >  T,,..„,  -f  T,.,^)  the  .soli('  powder  will  remain  suspended 
in   the  water. 


^KoUoiit  ■<,-ils(  hrift.  l:'.:2?,5  and  ChCm.  Wefkblad.  10:700. 
■Encyclopc.lia  Britayuiiia.  on  'Capillarity.' 


WIIV    IH)    M1NKKAL.S    KU) AT  .'  179 

'f  T,,.,  >  T,,.„,  -\-  T,„,,,  the  solid  will  leave  the  water  and  ro 
into  tile  layer  of  oil. 

Il  '',w,n,  >  T,,,,, -f  T,,.„,,  or  if  none  of  the  three  tensions  is 
Rreated  than  the  sum  of  the  other  two,  the  solid  partieles  will  eolleet 
at  the  boundary  hetween  the  oil  and  water. 

It  hardly  needs  to  he  said  that  here  we  find  something  very  close 
to  the  conditions  olitaining  in  the  flotation  process.  In  faet,  the  old 
Klinore  hulk-oil  flotation  method  fulfills  exactly  the  conditions  that 
Keinders  had  in  mind.  Helow  are  piven  some  tallies  of  results  obtained 
by  both  Heiiiders  and  Hoffmann''  in  an  experimental  way,  by  sus- 
pending u  definite  pondered  solid  in  water,  aduinj^  a  second  im- 
miscible litpiid,  and  shaking.  The  Ictt.r  ic  means  that  the  powder 
remained  in  the  water;  the  letter  it  means  that  the  powder  went  into 
the  oil  layer;  the  letter  .v  mci  .is  tliat  the  powder  went  to  the  surface 
8<'i.arating  the  oil  from  the  water,  and  .symbols  like  s{w)  or  s{o) 
mean  that  there  was  a  Rood  deal  more  of  the  powder  in  the  inter-face 
than  ill  the  bracketed  phase.  Similar  residts  were  obtaiued  with 
ciilloidid  solutions. 

Tvm.E  OK  Reinokks'  Rksilts 
Paraffin         Ani.vl 
Water  and  oil.  alcohol  CCl  .       Uenzene.  Ether. 

J^^o""    w  w(8)  w(s)  w  w(s) 

•^^l""- ws  ws  w(s)  w(s)  W(8) 

<5>l'Sl""     W  ws  W  8W  W8 

KaSO,     w(8)  ws  ws  BW  ws 

•Magnesium    ws  ws  «8  ws  ws 

^^^     8  8  8W  S  SW 

Malachite   so  s  s  s  sw 

2nS    s  8  s  s  SW 

^^^    so  so  s  8  a 

Hgl.. so  S  8  s  8 

Carbon    so  s  s  s  s 

Selenium    so  so  so  s  s 

Sulphur    so  so  o(s)  so  s 

Ilotrmann  worked  a  great  deal  with  ehemieal  precipitates  and  other 
artificially  prepared  products.  However,  the  laboratory  method  in- 
volved ou,;ht  to  be  good  in  the  study  of  flotation  processes  for  a  pos- 
sible method  of  floating  o.xidized  minerals.  Then  it  might  be  possible 
to  convert  a  successful  bulk-oil  process  into  a  frothing  process  in  the 
same  way  as  the  old  Elmore  bulk-oil  method  went  through  the  stage 
of  graiuilation  and  elassitic;ition  to  a  final  frothing  process  such  as  we 

'Zeit.  physik.  Chem.,  S3; 409,  1913. 


Ihd 


rnK  ha>tation  process 
Taui.e  ok  Hokkmann'm  Rh.sii.rs 


Wal    r  . 

('..SO. 

SllO 

AIMIll 

hnS 

H.iSO, 

ZllS 

Zn(J 

CaCO 

M^-iOM 

A I 

HafO 

CiiS 

I'l.CrO, 

<ii  I)    (  ' 

MoS      . 

CiiS    . 

Ki  O, 

Il.iCrO, 

I'liO. 

(• 

I'l.l. 

HuS 

HcO 

Af--I 


irid 


<'hlnr<» 

HmI\  I 

Kthir. 

Icilii 

Itli'fitini 

\v 

w 

W 

W    (  s  1 

ws 

ws 

\l    t    -    1 

Wrt 

WS 

ws 

^^  s 

\^  s 

El.n/ 


I'.lI.ltf.Tl 
Mil 


H  I  «■  •■  I 
SI  «  I 


8 
S(WI 


S  1  W    '  1 

^1  \\  ''  ) 

8 

s  (  \i  ■*  1 

S 

s 

s 

s 

K  (  W   t 

A\V 

S(W) 

-> 

,SW 

„ 

SCO  today.  I  liavp  done  some  work  filonir  thcs..  lines  and  liavi-  planned 
eonsiderable  reseaivli  work  in  the  Siune  direction.  Meantime  these 
notes  might  a.s  well  he  availahle  to  others  in  suKpesting  lines  of  ustd'ul 
research.  The  comments  to  he  made  on  the  al)()ve  tables  an>  without 
end,  hut  the  tables  are  given  here  mainly  to  suggest  the  j)o.ssil)ilities 
of  further  work. 

The  question  arises  as  to  whether  it  might  not  be  pos-sible  to  apply 
a  set  of  ine(iualities  such  a.s  those  of  Keinders,  or  oven  to  apply 
Heindei-s'  ine.iualities  dire.t,  in  the  prediction  of  results  for  froth 
flotation.  In  froth  flotation  we  have  at  least  four  phases — solid,  water, 
oil,  and  gas— unless  the  oil  happens  to  be  solul)lo  in  water,  in  which 
case  we  are  reduced  to  a  solid,  a  .solution,  and  a  gas.  Wo  have  inter- 
facial  tensions  between  each  two  of  the  pha.ses.  making  si.\  tensions  al- 
together, and  mathematical  expressions  covering  such  a  ea.se  must 
nece.s.sarily  l)e  much  more  comple.\  and  exhibit  a  greater  luimber  of 
possil)ilities.  The  problem  is  more  difficult,  b\it  it  should  be  capable  of 
solution.  Fig.  35  shows  a  fanciful  magnification  of  one  possible 
arrangement  of  the  i)arti<'les  of  sf)lid.  droi)lets  of  oil.  and  si)hcrules 


>»^-^-r^ 


WHY    1H>    MINKKVI-.S    HjIAT.' 


181 


of  iiir,  it)  till-  li<|iiii|  <>(  the  orc-piilp,  Im  intf  siiliji'di'd  lo  Hotatiiui,  at 
tlif  iiioiiiciit  wiii'ii  a  l)iilil>li'  lu'iriii!*  I"  niiM'  a  particlr  ol'  niiiHTal  to  tlie 
siirfaci'. 

Fif?.  .(()  sliows  a  pDssililc  way  of  applviiitf  R<'iii(ii'rs'  iii('<pialiti<'» 
direct  uitliout  any  iiioiiitiiatioii.  It  is  a.ssiirncil  that  the  oil  t'diiiis  an 
(•hVfln|)c  on   tlic   inniT  .surface  of   the   air   hulthh'  so   that    tlic   air   is 

AIR 


WATCK 


4? 


G/\S 


0/L 


MirjLKflL 


Fio.  35. 


nowhere  in  contact  with  water.  Mr.  Kickard"  ha.s  caUed  our  attention 
to  the  wori<  of  Devaiix.  piihlislicd  in  the  annual  report  of  tlie  Siuith- 
Honian  Institute,  in  which  it  wa.s  found  that  a  droplet  of  an  oil  wlien 
lijaccd  upon  a  plan"  surface  of  water  will  spread,  of  its  own  weiijiit, 


A  I  « 


»>\T  E  H 


M  I  rj  t  R  A  L  " 


Flo.   36. 


Fig.   37. 


until  it  forms  a  film  only  one  or  two  molecules  thick.  This  fact  allows 
an  explanation  of  how  the  small  amount  of  oil  used  in  the  froth- 
flotation  processes  could  be  sf)  efficient.     If  it  so  happens  that  the  oil 

■M.  it  «.  P.,  Sept.  11.  1915,  page  167. 


-i.f'.; 


ti^^t/'  -:%     -»...^U  ^ vu^i*-^T/r;:  vi*A.,cA;;^''.h^>r.tf^^ 


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MICROCOPY    RESOIUTION    TEST    CHART 

ANbl  u.id  ISO  lEST   CHART   No     2 


1.0 


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U^ms      1 2.5 

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^)  482  -  O300-Phon» 


182 


TIIK    FLOTATION-    I'HIKKSS 


uouhl  coat  tlie  inner  siirlai-L'  of  an  air  huhbli',  tliu  powdurtd  mint  nil 
would  he  abl.'  to  take  up  a  position  on  the  inter-faec  between  the  water 
and  the  oil  witliout  any  reference  to  the  air  in  the  bubble. 

By  reason  of  the  known  low  adhesiveness  of  oil  and  wal.T  il  is 
doubt  .'ul  if  the  air  l>ubbles  eo\ild  lie  completely  mantled  b\  oil,  as  tiie 
oil  would  be  too  liable  of  its  own  weiprlit  to  slide  down  to  the  bottom 
of  the  bubble  to  the  position  indicated  in  Fig.  ;i7.  Even  here,  the  oil 
could  <'arry  mineral  on  its  water  interface  (in  ease  the  oil  and  water 
do  actually  get  into  contact)  and  Keinders'  criteria  would  still  ajjpiy. 
Ill  a  Callow  flotation  machine  having  glass  sides  it  is  sometimes  pos- 
sible to  see  particles  in  ju.st  such  a  position.  However,  this  ease  does 
not  prove  that  the  top  side  of  tlie  bublile  is  coated  wiih  oil  or  mineral, 
wliile  the  bubbles  of  a  mineral  frotii  on  top  of  the  pulp  are  seen  to  be 
covered  eomi)letely  with  particles  of  mineral. 

If  the  mineral  tends  to  enter  the  oil  phase  completely  and  leave 
the  water,  llie  mineral  grains  present  only  an  oil  surface  and  in  case 
oil  droplets  tend  to  collect  at  the  inter-face  between  water  and  air 
tby  Keinders'  criteria)  we  could  have  the  ease  ilhisf -'at'd  in  Fif.  :iS, 


Fki.   38. 


This  ca.se,  as  well  as  the  one  illustrated  in  Fig.  ;U!,  would  allow  of  the 
air  liubliles  becoming  completely  covered  with  oiled  mineral. 

Other  phases  are  possible,  but  these  are  given  to  show  how  very 
feasible  it  is  to  get  an  explanation  of  flotation  in  terms  of  inter  facial 
tensions. 

In  an  investigation  i-ondiicted  by  the  .Minerals  Separation,  the 
'enntact  angle'  of  various  minerals  with  wafer  was  examined  to  tiinl 
at  what  angle  the  mineral  Iuk'  to  come  in  contac'  with  a  water  siirt'ace 
befoiv  it  was  wetted  and  could  sink."     A  glance  at  Clerk  Maxwell's 

«H.  L.  Sulman.  Trans.  Inst.  M.  &  M.,  1912. 


WHY    no    MINF.KAI.S    1L(X\T  .'  ]S:! 

I'aiiious  paper  on  'Capillarity,'  upon  whicli  KciiKJcrs'  work  is  luiscil, 
Avill  sugjrcst  immediately  the  explanation  of  a  contact  angle,  and 
that  it  is  the  result  of  a  certain  equilihrium  of  intcr-facial  tensions  of 
air,  water,  and  solid.  Valentiner"  ha.s  likewise  investijjated  the 
contact  angle  and  its  hysteresis  under  certain  conditions  and  has  con- 
nected it  very  definitely  with  capillary  phenomena.  There  can  be  no 
doubt  that  there  is  a  chise  parallelism  between  the  angle  of  hysteresis 
of  the  contact  angle  and  tlie  ability  of  a  mineral  to  tloat.  Hut  if 
we  go  no  further  than  to  observe  the  parallelism  we  cannot  designate 
the  statement  of  the  parallelism  as  a  theory,  although  we  might  bo 
able  to  predict  by  its  means  whether  a  mineral  would  float. 

To  go  into  this  a  little  farther,  and  indeed  nh.ng  the  line  suggested 
by  ;Mr.  Durell,  we  ought  to  consider  the  properties  of  the  surface 
layei-s  of  the  substances  involved.  For  e.xa.nple.  the  plane  surface  of 
water  in  contact  with  air  is  known  to  have  considerably  different 
properties  from  the  inner  bulk  of  the  water.     Tn  Fig.  nil  the  film  is 


Ji'fr^C£   f'/LX  or    i\'\Te.R 


BUL  ^    yy  f\T  E  R 


Fio,  39. 


shown  magnified  in  thickness.  It  acts  like  a  tightly  .stretched  elastic 
skin,  due  to  what  we  have  long  called  a  'surface  tension'  of  81  dynes 
per  centimetre,  as  is  u.sually  given  in  text-books.  (This  means  that 
for  a  strip  of  the  surface  film  one  centimetre  wide,  a  longitudinal 
tension  of  81  dynes  has  been  measured  at  ordinary  temperatures, 
and  there  is  a  definite  tension  for  each  temperature.)  This  tension 
of  the  surface  film  is  one  of  its  most  connnoidy  known  prop(>rties,  but 
some  other  interesting  points  about  it  are  given  in  tlie  following: 

Its  thickness,  varying  with  temperature  and  other  eunditions,  has 
been  estimated'^'  to  be  all  the  way  from  4X1"''  to  10  *  em.  Its  density 
averages  2.14  as  compared  with  1  for  bulk  water,  although  it  is  doubt- 
less mure  dense  at  the  immediate  surface  next  to  the  air  and  gradually 

»'A  Theory  of  Flotation.'  MctnU  iind  Erz,  11:4.t."i,  1914. 
'"Philonophirnl  Mngozinr.  20:502,  1910. 


1S4 


Tin:  I'l.iiiwTiDN   rnuciv- 


sluhirs  i.ir  into  tliat  (if  liulk  water.  'I'his  (•(insidcnitidii  i.roliahly  ex- 
plains Mic'  nidc  varialiun  in  the  results  of  tlie  ineasinvn:ent  of  tiio 
tliirkiies.s,  as  one  rnetlidd  nii<rlii  he  less  delicate  than  another  and 
lience  not  take  aeeount  of  some  of  the  layers  of  the  lilin  that  aie 
neiirly  hulk  water  in  their  jiropei'ties.  This  avera>re  density,  how- 
ever, is  illustrative  of  the  ujaL'iiitude  of  the  force  involved  hecauso 
water  is  a  siihstaiice  that  resists  compression,  and  it  has  heeii  cal- 
culated from  the  known  comprossihility  of  water  that  the  force 
necessary  to  compress  it  to  twice  its  (U'dinary  density  is  some  thousands 
of  atmospheres.  Such  a  eompression  should  liherate  heat.  and.  in  fiict. 
the  heal  liberated  when  a  definite  area  of  new  surface  film  is  loriui'd 
has  been  measured  and  found"  to  lie  0.00:]].")  ,.;d.  prr  si|.  em.  Hi'in>,'  so 
lii>:lily  compressiu.  its  siiecilic  heat  ini^dit  he  expected  to  he  ditVereiit 
from  that  of  hulk  water  and  has  been  measured  as  heiiiir  nearly  0.4.') 
instead  of  1.     This  low  speciiic  hrat  approximates  that  of  ice. 

One  imj)ortaiit  property  of  this  lilm  is  that  it  will  often  take  iij) 
ilissolved  sulistaiices  in  difl'ereiit  proportion  from  the  amounts  in  which 
tliey  are  taken  up  in  tlii'  hulk  solution,  and  there  is  always  a  definite 
e(|uilihrium  hetuc^n  the  two.  This  is  known  as  surface  eoncentratiou 
or  -surface  adsorption.'  and  has  heiMi  dealt  with  mostly  in  colloiil 
chemistry,  where  the  larj;e  amciint  of  surface  of  the  finely  divided 
solids  is  lar-re  in  .•omparison  with  their  wei<jht.  Tn  case  a  fjreater 
proportion  of  the  suhstanee  is  concentrated  into  the  film  than  there 
is  into  the  hulk  water  we  have  positive  adsorption;  and  in  the  revcrs.' 
case.  nei,Mtive  adsorption.  The  properties  of  these  iiiter-facid  films 
have  heeii  foun-l  to  he  Kreatly  modilied  hy  small  amounts  of  dissolved 
siihslaiices  aii<l  the  i)ro|)erties  of  colloids  are  lieiice  likewise  fjreatly 
ehaiisred  The  importance  of  the  study  of  inter-fai-ial  films  liecomes 
ohxious. 

Finally,  there  is  a  most  important  fact  about  the  film  of  water  in 
contact  with  air.  Jt  has  bei'ii  fouml  that  there  is  a  difrereiice  of 
potential  of  O.O.").")  volts  between  the  two  surfaces  of  the  film.'-  The 
density  of  the  static  electric  charjre  at  this  potential  is  4X10' 
coulombs  per  s(|.  cm.  This  electric  chart;,'  is  mark.Mlly  influenced  by 
electrolytes  in  solution  and  can  be  inerea.sed  or  deerea.sed.  even  pass- 
irii;-  tlirou!.'h  zero  and  then  iiiereasintr  in  tlii'  opposif,  sij.'n.  All  inter- 
facial  liliiis  have  liki'uise  liecii  found  to  be  cliarf.'ed  in  one  way  or 
other.  Industrial  applications  of  this  fact  are  l(>i,'ion.  All  the  tech- 
nical liandlin<r  of  days  is  now  conditioned  liy  the  use  of  electrolvles  in 

"/hi(/..  2ii:.'i'il',   i;n(i. 

y-Ihi,l..  ■:i:2'M.  1!H1.  .-mfl  :jN:.1(;7,   lint. 


WllV    IK)    MINKHALS    KI.OAT.' 


is:. 


tilis  iiiaiiiKT,  jiiul  the  iiiicstioii  of  .'imilsiims  of  all  kinds  of  oils  ii, 
wiil.T  is  closflv  hoiiiid  uj.  with  it.  Cottivirs  piTripitatioii  i)r()c,.ss  .iT 
snsj)cinli'J.  particles  (it  snjids  or  li(|nids  in  irascs  tines  not  escape  these 
considerations.  Small  particles  of  solid.s.  licpiids.  or  erases  suspended 
m  either  liquid  or  ^'a.seous  media  are  ton  .d  connuonly  to  carry  elect>ic 

••liiirges.  due  lo  various iihinations  of     .ctors  which  atVect  the  douhle 

electric  layer  of  the  inter-facial  tilnis. 

Since  the  size  of  iiiiuiy  of  th.'  j.articles  of  minerals  tr.aird  liy 
dotation  is  of  the  same  niap.itnde  as  that  of  many  colloids  wu  cannot 
esc;ii)e  from  calliii},'  oiv-slime  •'coarse  sasj.eiision  colloids."  and  mu.st 
apply  all  the  laws  of  colloid  chemistry  to  our  problem. 

The  (deetrif  charges  on  siispemled  pa-ticles  allow  another  possible 
•■xplanation  of  flotation  |>lienoiiiena.     We  find  in  some  of  the  e<,lloi,I 
chemical  literature''  that  i|uartz  particles  when  .su.spended   in  waler 
are  negatively  charged,  pyrite  partich'.s  [x.sitively  charged."  oil  drop- 
lets  are   negatively   charged,   and   air   hiibl.les  negatively   charged. '■• 
The  charges  are  .somewhat   small   compared  with   the   weight  of  the 
partiides,  so  that  they  are  hardly  strong  enough  to  cause  negatively- 
charged  quartz  to  stick  to  positively-charged  pyrite,  as  they  can  have 
only  a  few  i)oints  of  contact,  and  currents  in  the  water  could  easily 
tear  them  apart.      However,   the  negatively-charged   tiroplet    of   oil, 
which  is  repeUed  from  a  negativ.dy-charged  particle  of  .piartz,  can 
wrap  itself  around  the  positi\ely-charged  pyrite  partiide  so  that  they 
will  stick  together,  and  the  same  applies  to  air  hubl.les.     The  other 
sulphides  known  to  be  flotative  have  positive  charges  when  suspended 
in  water  or  can  be  made  to  assume  positive  charges  by  the  use  of  flu- 
proper  amount  of  the  proper  electrolyte.     So  it  can  be  s.>.'n  that  the 
applicaHon  of  the.se  principles  gives  no  difficulty  in  <xplaining  flota- 
tion from  an  entirely  new  standpoint.;-     Th  ■  lartre  riTect  of  a  small 
amount  of  sulphurie  acid  on  the  conditions  of  flotation  does  not  .s<'(  m 
strange  at  all  in  this  liglit.  and  we  do  not  have  to  retreat  to  the  purely 

'''KoUiiifl  Clifiiiisvlic  nrihrfte.  2:S4. 

'^/.fittichrift  fur  pliysikalisrhc  ('hemic.  S9:!ll,  ](1]4. 

I'Scp  foot-note  No.  10. 

Tit  would  appear  that  at  the  instipatinn  of  ,J.  M.  Callow,  the  Mellon 
Institute  of  I'ittsbuPB,  under  the  dirertion  of  R,  C.  Bacon,  also  formulated  this 
.«anip  theor.v,  and  for  a  long  time  has  done  research  work  in  this  direction 
this  work  and  continuation  of  It  at  the  Bureau  of  Mines  at  Salt  Lake  City 
seem  to  support  (he  louic  of  this  thenry.  A  pauer  o.w  :hr  i.-itv.c  o-hi^.-.t  ,-..- 
read  by  Mr.  Callow  at  the  Oetoher  meeting  of  the  American  InstUute  of 
Mininf?  EnRineers  in  Salt  Lake  City      See  page  2,11  of  this  l)ook. 


],sti 


Tin:    FI.UTATION    "HOCK.- 


iiiiiif,'iiiary   sii|ipositiiiri  tlial  ipsiiidtir   ]irt'.s.suiv   is  acting  tlirougli   tho 
siirt'a<'t.'  of  tl:i'  iiiincral.  as  docs  .Mr.  Durcll. 

Tlic  iiitcr-faci.il  tension  and  tlie  cliai'fic  on  the  intcr-t'acial  film  arc 
two  (litl'ci-cnt  jiliysical  jji-opcrtics  of  one  and  tlic  same  tliini,'.  I  have 
shown  that  an  appeal  to  either  property  is  enough  to  hnihl  np  a  work- 
ing picture  of  flotation  phenomena  that  is  simpler  and  nuu-e  prol)alile 
tlian  that  of  .Mr.  Durcll.  I  do  not  know  how  much  there  is  in  his  cou- 
lention  that  air  huhiilcs  will  not  attach  themselves  directly  to  the 
l)articles.  or  thai  only  the  dissolved  air  can  thus  attach  itself;  it  may 
lie  that  this  is  .,11  correct,  without  interfering  with  the  explanation 
th-!t  I  have  jiut  for\iard.  However,  I  hesitate  to  acce|)t  .such  a  coti- 
ce|>tion.  The  underlying  cause  of  the  tensions  and  of  the  electric 
c'liargcs  is  the  same  thing — some  strange  molecular,  atomic,  or  other 
force  manifested  in  'adhesion,'  "cohesion,'  or  even  'gravitation.'  if 
you  [dease.  >.'()  one  can  claim  that  electric  charges  carry  the  whole 
explanation  of  Hotalion.  nor  can  it  he  stated  that  it  is  merely  a  ([ues- 
lion  of  a  Irdancing  of  inter-facial  tensions.  Hoth  will  douhtless  have  to 
he  considered. 

Although  much  more  could  lie  said  on  the  sulijcct,  I  have  only 
atleinplcd  to  point  out  that  there  are  certain  scientilic  princijiles  that 
can  he  ap|)lied  to  our  problem,  with  great  chan.ees  of  success,  in  bring- 
ing us  nearer  to  a  definite  understanding  of  flotation.  Physical  chem- 
istry has  been  a  recognized  tool  of  metallurgists  for  some  lime,  al- 
though litth^  used  by  most  of  them,  and  now  a  particular  branch  of 
phyr,ical  chemistry — colloid  chemistry— is  beckoning  to  us  alluringly. 
-Ml  (pieslions  of  the  treatment  of  orc-slime  should  be  stuilied  in  this 
new  liglil.  The  results  of  aii  apj)liiation  of  tln.s  idea  in  our  own 
laboratory  have  been  astonishing,  and  we  hope  that  we  nuiy  soon  be 
alilc  to  pnMisii  them. 


WHY    IS    rKdlATION  .' 


l.s; 


WHY  IS  FLOTATION? 

(P^oiii  the  Miiiiii;/  (111(1  :S(.tfiitilic  Press  of  Otloher  30,  1915) 

The    Editor: 

Sir  Mr.  Durcll's  article  on  this  subject  in  your  issue  of  .Septem- 
ber IS  is  interesting'.  I  helii've  that  an  exchange  ol'  ideas  on  this 
subject  is  very  desirable,  and  it  may  be  tiiat  some  of  the  information 
that  1  have  collected  may  be  of  interest  to  the  readers  of  the  Press. 

The  arguments  which  .Mr.  Dun'H's  article  presents  are,  briefly, 
tiiat  tioatalilc  particles  eainiot  attach  themselves  to  previously  formed 
bubbles,  but  nuist  be  floated  by  bubbles  which  form  themselves  on 
the  surface  of  the  particles  so  that  there  is  no  surface  film  of  water 
between  the  particle  and  the  air.  To  explain  the  formation  of  these, 
Mr.  Durell  assumes  that  the  water  is  super-saturated  with  dissolved 
air  and  that  there  is  a  certain  amount  of  "occluded"  air  on  and 
in  the  surface  of  the  particle,  and  that  these  combine  to  form  bubbles. 
That  this  occluded  air  may  be  present  is  certaiidy  pos.sible,  but 
that  it  would  lie  lilieratcd  with  sufficient  rapidity  to  float  the  particles 
does  not  seem  probable.  That  the  water  in  a  ^[.  S.  type  of  machine 
is  supersaturated  with  air  is  also  probable.  Imt  I  cannot  see  how 
the  w:iter  in  a  Callow  or  other  pneumatic  machine  can  become 
greatly  super-.saturated  l)y  the  introduction  of  air  through  a  coarsely 
porous  medium  such  as  canvas  twill. 

The  idea  of  super-saturating  the  water  with  air  is  not  new.  As 
early  as  1007  D.  11.  Norris  patenterl  this  process.  (('.  S.  patents 
No.  864.856  and  873,586.)  Mr.  Ncrris  saturated  water  with  air  at  a 
prcs.sure  of  .several  atmospheres,  and  introduced  it  into  an  open  tank 
at  normal  pressure,  where  the  exces.s  air  formed  what  he  called 
'"inflnitely  small  nascent  bubbles  of  gas"  which  were  suppos-d  to 
float  the  sulphide  particles.  So  far  as  I  know,  this  idea  has  never 
been  put  into  successful  operation. 

As  to  :\Ir.  Durell 's  statement  that  the  dissolved  and  occluded  air 
are  indispensable:  if  it  is  true,  previous  boiling  of  the  pulp,  which 
would  drive  out  all  of  the  dissolved  and  some  of  the  occluded  air. 
should  interfere  considerably  with  flotation,  especially  in  a  i)neuniatic 
macliine.  I  have  seen  this  done  in  the  laboratory  of  the  General 
Engineering  Company.  The  subsequent  flotation  took  place  with 
pv.M 


.M,.    tl.„    o„. 


L-u:;i;i:css 


viicii  inc  siiniG  ore 
was  floated  without  boiling  of  the  pulp.  Furthermore  it  has  been 
my  oliservation.  that  when  a  carbonate  ore  is  treated  with  soluble 


i- 


188 


Tin;  :■  i.d'r \Ti(i\   I'UdCF.sr 


siilpliiW.'s  Inr  111,,  i.iirjms..  ,,r  f(,riiiini;  nn  artilirial  liliri  m|  miI|)1ii.I- 
on  Ilie  .siirl'acr  of  the  luin.Tal  parti. ■|,s.  niiicli  hrttci'  ivsiiUs  aiv 
obtain. m1  wjirn  a  small  aiiionnt  of  alkali  is  addiMl  to  tiif  pulp  to 
iVMiov  anv  ira.Ts  of  1I,S  ^ras.  This  can  also  !,.•  ac.-oniplisii.M|  hy 
the  nsr  of  SO,,  uhirl,  ivads  with  tlir  \\  S  t,,  form  sulphur  anil 
ll_,().  ami  (liM's  not  h-avc-  m  alkaline  pulp.  Were  .Mr.  Dmi'll's 
liypolhcsis  truo.  this  ^ras  sliouM  l.c  JMHriirial  rather  than  .Irtriuicntal, 
ami  It  wmihl  serm  ijiat  the  f/i^m-ral  rtVrci  ,.f  arlitirial  sulphidinir 
woiihi  lir  tn  r.'ilucf  the  amount  of  ,,c,-lml,il  air  rather  Ihan  im-reas,. 
It,  as  snme  of  it  Would  undoiilitedly  he  displaced  hv  II_,S  which  would 

latei-    he    I'cniovecl. 

I  cannot  ajrree  with  Mr.  Durell's  statement  that  floatable  particles 
"ill  not  attach  them.selvos  to  previously  formed  air  huhhles.  I  nnde).. 
stand  that  in  the  suit  of  the  .Minerals  Separation.  Ltd,,  r.  .Miami 
<'oi>per  Co..  hear.l  at  Wilmiiifrton  .May  lltl.-).  the  plaintitT  i)r...sented 
*"  ""•  *'"!"■<  ;i  nioviiii,'  picturi'  of  an  e.\|)eiiment  in  which  it  was 
shown  under  Just  what  condiilons  the  j. article  would  attach  it.self  to 
th..  hulihle.  Aside  from  that,  it  is  not  a  far-fetched  assum|.tion  that 
the  air  huhhles  in  an  oil-emulsion  iiave  mantles  of  oil.  Their  property 
of  frothiiif,'  would  so  indicate,  and.  in  that  case,  the  surface  films 
of  water  surronndiiiL'  them  would  not  ditVer  materially  from  the  films 
surrouiiiliri','  drops  of  oil  siispemled  in  water.  That  such  ilrops  of 
"•'  '••!"  '■""•■'•I  I'Mtahh-  particles  out  of  an  ore  can  -■asily  he  proved 
hy  shakni",'  oil  with  a  mixture  of  {ridena  and  sand  susp(>iided  in  water. 
When  the  oil  has  collected,  the  dro])s  will  he  .seen  to  l)e  covered 
with  the  Efalena.  If  we  imatrinc  the  centres  of  these  drojis  to  he  filled 
with  air  instead  of  oil.  we  have  conditions  whicii  miu'lit  easily  hold 
in  an  ai-tual  flotation   machine. 

On  the  whole.  Mr.  niirell's  hypothesis  does  not  sci'in  to  conform 
with  actual  tiotation  i)ra<'tice.  There  are  other  theories  tliat  explain 
tifitation    in    hetfi'r   conformity    with    known    scientific    facts.      T.    J. 

Hoover,  for  instance,  in  his  1 k  'Concent rat intr  Ores  hy  Klofation." 

presents  a  eonsistent  theorv.  and  J.  >r.  Callow  i)resented  a  paper 
to  the  rtah  Section  of  the  .American  Institute  of  .Minin}^  Engineers 
111  which  were  .s(-f  out  some  theories  has.'d  ,,n  experimental  work 
done  at  the  M,.llou  fnstitute  and  at  the  local  station  of  the  V.  S. 
Bureau  of  .Mines.  This  paper*  will  undouht.dly  he  piihlishod  soon 
in  the  transaetions  of  the  Institute. 

.T\MFS    .\.    BloCK. 

Sail    i,ake  <iT\-,  (^ictolier  ti. 


*See  page  2,'!!  of  this  liooli. 


AlU-FUnlll    ri.uTAriii.V  —  II 


]!-'. 


AIR-FROTH   FLOTATION— II 

I  From  Ihc  Mniin;/  ami  Sciitilitir  Pn:ss  of  Novcii.b.i-  ti,  i'ji5) 

I  hi  our  is.siR'  of  Ortohri-  H;  wf  fiavu  an  cxrcriit  I'mm  the  s]>fiM-li 
iiuulf  hy  .Mr.  \V.  A.  .Scott,  comusi'l  tor  dt'lViidaiit  in  tlic  casf  of  Minerals 
Separation.  Limited,  r.  .Miami  ('oii|)er  Compaii.v.  We  follow  this  imu 
with  leiii,'thy  (jiiotatioiis  from  ihe  sju'eehes  of  Mesvsrs.-- Henry  1).  Wil- 
liams and  \V.  Houston  Keiiyon,  of  eoun.si  1  for  the  eom|)lainant.  In 
the  lirst  e.xeerpt  .Mr.  Williams  (liseiis.s«'s  the  article  l.y  the  three 
students  at  the  University  of  California,  as  piildished  in  the  eolhsie 
iii'i'.'ii/.ine.  Tin  Califoniui  Jaurnul  af  T,  riniul, ,,)!/.  The  major  jxirtion 
of  that  article  appeared  in  our  issue  of  July  ;jl.  UHi),  to  which  the 
leader  is  referred*  in  order  to  follow  the  lawyer's  remarks.  In  the 
second  and  third  excerpts  Mr.  Keiiyon  discusses  .some  of  the  ])liysics 
of  the  flotation  process.  Of  course,  the  reader  must  remember  that 
this  exposition  of  the  suh.ject,  like  that  of  Mr.  Scott,  is  not  to  he  taken 
as  a  seientilic  thesis:  it  is  essentially  an  <  .r  pnrU  e.x|ilanatiou.  hut  even 
as  such  it  is  e.xtremely  interesting  to  metallurgists.  The  first  pateni 
in  suit   to  which  reference  is  made,  is  No.  M.!.'),120.— Hmrdu.  | 

Mk.  Williams:  The  California  Juurnal  of  Tiduiologn  is  evidence 
of  the  interest  that  the  metallurpical  world  took  in  the  Elmore  process. 
The  title  is  'Experiments  (ii  the  Elmore  I'rocess  of  Oil  Concentration.' 
The  conclusion  is: 

"The  work  aliove  outlined  suggests  niany  lin.'s  of  furtlier  investi- 
gation, and  as  these  ■  ome  to  be  worked  out,  the  process  will  become 
more  valual)le  and  of  more  general  application." 

What  proces.s?    The  Elmore  process. 

Fn  l!tO:i,  the  Elmore  process  was  a  hope  of  the  metallurgical  world. 

Incidentally,  the  students  discovered  something  else,  and,  for  the 
first  time,  gave  to  the  world  the  foam  effect.  Full  (iisch)surc  as  to  a 
mode  of  operation  which  would  produce  an  oil  foauL  they,  for  the  first 
time  in  the  history  of  metallurgy,  gave  to  the  world. 

That  was  an  incident  of  their  careful  invi'stigation,  but  tlie  arti.de 
itself  is  on  the  Elmore  proces.s.  and  it  says  that  the  Elmore  proces.s  was 
then  a  hope  of  the  metallurgical  world. 

TiiK  Coi-RT :  Mr.  Williams,  if  there  was  a  disclosure  of  the  proces,s, 
filthough  a  misnomer,  what  would  be  the  effect  of  that  disclosure? 

Mr.  AVii.i  I  \ai'<  :     Tl'e  tiHine.  oliviouslv    h.r.:^  •.•.rih'.-.-.cr  i.-.  .1..  -.;-:!'.  [t 

The  CoiRT:    No. 

•Sep  page  102  of  this  honk. 


190 


TIIK    ri.oTATluN     l'|i(K'h> 


.Mii,  Williams:  I  \vj,s  piirlifularly  dim'tinf?  .„y  attention  to  the 
tac't  tliat  .Mr.  Sh.rulan  look  tlios,.  last  tliriM-  lines  as  something  whidi 
was  .Imcte,!  soKly  and  wiiolly  to  tl,at  small  part  of  this  artirlc  which 
dials  with  the  foam  i^tfeet. 

Till-:  ('(PiHT:    Oh,  I  luiderstand. 

-Mh.  Williams  :  And  1  wits  i.ierely  ])ointiiifr  to  the  fact  that  those 
lines  n.usl  have  referred  to  this  Klmore  proee.ss  as  a  hope  of  the 
iiiitallurj^ieal  world. 

The  foam  etTeet  here  dis.-losed.  uhieh  is  reeommeiHled  as  employ- 
nit'  f<.;i',;  of  oil~it  hei.if,'  eh-arly  shown  that  nothing  else  is  worth 
aiiythnii?— 8.l»',t  of  oil  and  .salt  solution,  an  ore  eontaining  lifjht  flaky 
minerals,  .siieh  as  molylnlenite ;  and  another  ,)ne  of  the  same  kind  is 
frraphite,  and  1  do  not  know  any  others— <'ertainly  not  copper,  cer- 
tainly not  zinc,  (ialena  and  hlende  are  not  flaky.  (;alena  is  almost 
'•ulMcal  ni  its  fiacture.  They  call  attention  to  the  study  of  the  frac- 
ture of  minerals.  They  worked  out  this  foam  effect,  which  they  give 
to  the  world,  with  the  recommendation  that  8.!)',;.  of  oil  he  used,  as 
something  which  may  i)ossihly  he  useful  with  light  flakv  minerals, 
and  that  became  a  part  of  the  constructive  knowledge  of  the  world 
in  November  1903. 

It  is  remarkable  that  it  was  buried  and  lost,  and  that  it  took  three 
years  of  litigation  to  unearth  it.  That  is  quite  remarkable,  especially 
that  It  should  have  been  ))uried  and  lo.st  in  the  I'niversity  of  Cali- 
fornia, whicii  is  in  the  heart  or  the  centre  of  the  important  mining 
interests  on  the  Pacific  Coa.st,  and  in  the  Great  West. 

Hut  that  is  all  there  is  there,  and  the  most  significant  thing  about 
It  IS  that  It  tells  the  investigator:  We  have  tried  2.1^,',  and  the  i-esull 
is  hopeless.  We  have  tried  5.:i';; ,  an.l  the  result  is  almost  as  ba.l.  Hut 
we  have  tried  S.H'^  and  there  is  some  hojte  in  that.  Now,  procVed  ■ 
investigate. 

Hut  very  ovidentl.v.  nobody  proceeded  and  investigated.  There  is 
iK.t  any  practical  art,  unless  it  be  Elmore.  There  was  not  anv  mill 
that  made  any  use  of  any  of  these  patents  that  have  been  referred  to. 
Ilaynes  lightly  touched  upon  :  Everson.  the  foundation  of  the  de- 
fen.lant's  ca.se— why  these  very  students  in  this  article  tell  the  exact 
truth  about  Everson.  I  am  sorry  they  di.l  not  write  more,  because 
th..y  would  have  ])een  impartial,  and  they  would  have  possibly  given 
us  a  fair,  iinbia.sed  inti>rpretation  of  the  patent. 

•Tn  I88fi  Carrie  J.  Everson  of  Chicago*  contribute.!  the  idea  that 
•In  tier  first  patent.  No.  :U!),1.17.  she  is  described  as  "of  ChlcaRo,  Illinois," 
Imt   in  No.  471,174  she  is  said  to  be  "of  Denver,  Colorado."— Editor. 


AIU-KKOTII    ll.uTATKiN- 


11(1 


lliv  niiiciiitiatioii  w;is  iiuk-d  hy  tlic  pn'sciicf  »(  an  ac-id  solution,  and 
[lalcntt'd  tile  same." 

That  is  just  e.xattly  what  Carrie  Kverson  did  eontrihute.  It  is  an 
exaet  statement,  and  tliat  is  preceded  i)y  reference  to  anotlier  pat.'iit, 
which  the  defendant  has  not  seen  tit  to  refer  to,  although  it  iuw  ti^fiired 
in  some  other  litii(ation— tlie  patent  of  Tunhrid^'e,  erroneou.sly  liere 
spelled  •Turni.ri<lsre.'  That  is  set  forth  liere  as  the  first  patent  for 
utilizing,'  oil.  and  its  date  is  ^iven  as  IST.S.  Hut  it  is  of  slitfht  >■  le- 
vaney.  and  the  defendant  has  not  relied  ui)on  it,  and  it  is,  as  your 
Honor  will  note,  later  than  Ilaynes. 

As  (>  matter  of  fact,  the  reference  to  this  pat<'nt  would  indicate  a 
study  of  the  Everson  patent,  because  th.'  Kverson  patent  di.sclaims 
the  Tunhridge  patent.  It  does  so  with  <piite  some  lalior.  It  is  the 
thir'g  that  Carrie  Everson  had  to  distinjjui.sh  from;  that  I  tliink  ac- 
counts for  the  reference  to  that  patent. 

These  students  prohahly  inve.stij^rated  the  patent  situation,  and  so 
they  referml  to  the  Tunhridge  patent  and  the  Everson  patent,  and 
they  tell  the  exact  truth  of  the  contrihution  of  Carrie  J.  Everson  to 
the  art  of  the  idea  that  the  concentration  was  aided  by  the  presence 
of  an  acid  solution. 

Then  the.se  youn-,'  men  say,  and  they  say  truthfully: 

■■lint  the  absence  of  a  successful  method  of  separating  the  mineral 
from  the  oil  prevented  the  practical  application  of  these  prior 
patents." 

Well,  they  do  not  tell  the  whole  truth  about  that,  but  that  is  un- 
doiilitedly  one  of  the  reasons,  and  the  important  thing  is  that  these 
prior  patents.  Tuniu^idife  and  Everson,  were  not  practically  applied. 
That  they  w.-re  not  capable  of  practicable  application  would  be  the 
rea.sonable  presumption,  but  that  is  the  fact.  And  then  these  students 
go  into  the  subject  of  the  removal  of  the  oil.  Of  course,  with  17.1% 
of  oil,  which  is  1342  pounds  of  oil  to  the  ton  of  ore.  a..d  if  out  of  the 
ton  of  ore  you  got  700  lb.  of  concentrate,  that  would  be  a  fair  average. 
With  these  342  lb.  of  oil.  you  see  the  oil  would  be  about  oO^J  of  the 
concentrate.  You  would  have  a  great  mass  of  oil  with  the  concen- 
trate, and  unless  you  could  successfully  get  rid  of  thit  oil,  it  would  be 
troublesome;  and,  again,  the  cost  of  iiiat  oil  was  such  that  it  must 
be  possible  to  recover  and  use  it  over  again.  It  has  acted  merely  in  a 
physical  manner.  Tt  lias  not  change<l  its  constitution  at  all.  So,  if 
you  could  brinp  it  out,  senar.ate  it.  and  send  it  tbrr-.ijcb  s^-a-.-.-.  f!-...--. 
was  some  hope;  it  was  Elmore  who  did  that. 

The  students  say  that  burning  of  the  oil  was  tried,  which  left  a 


IfiL' 


Till.    H.cpT  V'l Kin     I'UocKss 


tllDicilIt  n-SKluc  ti,  ii,;,|    .■n,,|  il,,.  1.,,.,,  .  .     , 

,       ,,       ,    ,  "■"■■'""  '11''  l.'l^','  roii.siuni.il. )ri  ol    I   ll   llliidi'  Ihr 

""■"""I   too  ..x,,..„s,v...     Tlw.t    l.s  „n,|n,.l„,.,llv   ,,„., 

■•"   ""SMol   until  .iMly   1IMI.M1U.,  tins  .liftinilty  ua.s  ov,.-,-,,,,,,.  I,v 
~-.l  a  sp,.n.l  MiaWui...  sniMlar  in  mns.  ,vs,,,.H 

.s  .1  iM  suear  .aH..n...s  an.l  in  milk  a,„l  ,.,■,,.„,  s.parai.on      This  

tnl.m.onl.vMr.  KlniorMl,..nu,ad,.,lH.,H.o,.,.,.s,Va.sihl..'' 

N.nv.  w.'uillno„.  |M.„.  iha,  tl„.yn„.antl„.  ,„.„n.s.„f.„l  „. 

;;';'"•,  ""•- ..-"-"^"-"  .•,.,■,.  looking  ai  ,i  ..mv  ,,. „„.  .,,:■. 

">"t  ol  soin.th.n,.  w„.,.|,  „til,....l  ,.i|  ],.  „„.  ,.,.,„.,.n,rat.on  „|  ,„vs  -^ 
i"^;  ".'.v  nn,  ,.„n,.,.,.n,.,l  particularly  will,  ,„..tl,„.|s.  l,ut  .h.v  uviv 
'-kin,'  at  It  a  ways  Iroin  that  viewpoint:  that  is  whv  th..v  r".!'..,-  to 
lMnl„-„|p..  ami  why  ,lu,v  ,■,,,.,  ,„  k,.,,,.,,,.  ,,„  „„.,.„  .;  ,,,,^- 

''.•  M,.„.s,.on  n,..,nin.  tln.ni.h  h.iv  that  th.-  Kvet.on  pat-nt,  wlu,-. 
->   say  has  proved  ot"  no  pra-ti.al  valu,..  makes  anv  su.,es,ion  of 
tl'.tation.     Kverson  merely  eontrihute,!  the  U.S.  of  a,-i.r 


Mk.AMu.-ms:  I'no..  to  ,h,.  invention  of  ,|„.  ,i,.st  pa,..nt  in  suit 
•""'  '""'^"'«  ""'•^'  '"  "'"'f  ""■"  'li'l.  -.■  lin.i  that  wet-eon..entration 
Pn,e..s.ses  were  the  solution  of  the  oro-eo„ee„tration  prohlem  Thev 
^|■.■^.■  he  ,>roees.s<.s  that  have  heen  .le.serihe.l  here.  an,l  that  I  nee.l  not 
'  e..r,he  ajrain:  p,-oe,.ss..s  that  depend  „pon  gravity  and  shaking  and 
>  -t.on  of  ,„H.|y  ,.n>„nd  ore  suspended  n,  movin.  water,  the  sepai^Uion 
.l.1..-nd,n,.  upon  the  ditTerenee  in  sinkin.-power  of  the  metal  an.i  the 

extent  stdl.  but   that  are  hein^,.  superseded  in  the  la.st  two  or  three 
>ears  to  an  a-ston,shinir  decree  hy  the  processes  of  the  patents  in  suit 
Ao.n,  these  wet-.-on-^entration  proees.ses  advantage  wa.s  taken  of 

>e  faet  that  the  metal  had  a  higher  speeiHc  gravity  in  the  avei. 
han  the  ganfrue.  an.l  the  laws  of  nature  were  followed.     The  heavier 
.Inn.  wa.s  a  l.,wed  t..  settle,  and  eireumstanees  and  conditions  were  .s> 
'•ontrol  ed  that  ,t  would  have  a  chance  to  settle  away  while  the  .an,, 

:>..  .1  -.0  le  t  suspend..!.  The  ,an.ue  would  he  floated  in  n.ul-hulk 
"1  the  hqui.l.  and  up  an.l  down  and  all  aroun.l,  and  finally  floated  off 
oviT  a  dam. 

Hut  all  wet-concentration  p,oces.ses-and  the  machinery  for  car 
n.ngr  them  out  ha.s  exercise.l  the  ingenuity  of  inventors  for  thirty 

f.!ctV;  Ir''"'""'™""''*'""  ^""'''^''  ''''"  "^'''^•''^  '^'^  «'i>"^'  «"<!  tl:e 
f.Kt  that  the  concentration  was  hy  such  proees.ses  raised  a  hard  an.l 

fast  hm.tat.on  to  the  extent  that  you  .-ouhl  .rind  ore.     The  .rin.lin. 
must  he  co.ir^i."      The  .—--:-.. .i;....  •  -  f^'oiuum 


...  -       :  ::e  ^:-.-:;;:::;^.  ;p;;,j  p„.  ^,,  ^j^^ii^^  ^^  j^  produce  the  mini- 
'"um  of  metal-dust:  an.i  so  .rin.lin.  machines  were  invented  to  that 


MK-H(ori|    H.iflMKiN 


v::\ 


.•11.1,  I.,  prvv.'iit  111,.  i.n»lucti(.n  ..f  tli.'  liii..  dusl  iikf  ]mrti,.l..is  ..f  lal 

in  til.-  ^r.iienil  j,'riii(liiij,'  .if  fii,.  ,„v.  AM  w.'t-.'oii.viitnilioii  |.r.M,-.,s.js 
aiv  usi'k-iiti  on  slimes.  Tlicy  will  n,it  srlll.'.  They  will  ,,..1  om-v  Ilir 
laws  ,>{  uravity.  Tlicy  will  slay  up  wiili  tli,'  hhuhw'.  'I'li.'y  will"  tl,,al 
<>t\  with  llic  f,MiiK'n.'.  Th.'y  will  run  to  wast,-.  And  hm.".'  wv  liii\c 
tli.'Sf  tailings  in  Australia  and  Iutc,  of  millions  of  tons,  wli.iv  tlu- 
.slimed  metal,  the  linest  of  the  iiK.ial,  has  all  run  oir,  heeaiise  it  eould 
not  he  recovered.  With  siieli  eoii(..'ntratioii  i)ro(.es.ses  the  hest  that 
eoiild  he  (hiiie  was  from  »i()  to  7(»';<'  recovery.  Prof.  Fulton  (?ave  TO", 
as  the  outside  limit— GO  or  l()';i  of  the  sulphide  m,.tal  in  the  ori^'inal 
ore.    And  yet  men  persisted  in  using  that  pro(.ess. 

Klmore.  atmut  the  opening  of  this  century,  ahout  1900— his  jiat 
eiits  were  a  y.'ar  or  two  earlier— ..aiiie  in  with  his  process  to  reverse 
the  laws  of  nature.     Instead  of  Uridine;  th.-  heavier" tiling  at  the  Ixit- 
tom,  Klmore  said:  "I  will  carry  it  to  the  top." 

A?nin  a  process  nseies.s  on  sliim..  Again  a  proc(..ss  rcjuiring  coarse 
grinding  as  liefore.  The  concentrate  at  the  top  now  instead  of  at  the 
iM.ttom.  The  theory  of  operation  was  an  oil  lake.  I  like  that  word 
'lak.'.  ■  It  is  used  hy  the  California  Jounml  student.'r— an  oil  lake. 
Air  ..iitrainment  was  fatal.  Ingenuity  was  ex..rcised  to  so  mix  the 
oil  lake  and  the  ore  as  not  to  entrap  air.  Oil  emulsion  was  fatal. 
The  amount  of  oil  we  know  was  100  to  .'{OO'-;.  on  the  ore.  And  yet 
men  did  that  thing.  .Men  paid  that  price,  and  the  loss  on  every  100 
It',  of  oil  was  n  or  10  Ih.  at  each  cycle.  The  other  90  lb.  had  to  be 
taken  out.  and  preserved,  and  ii.sed  over  again. 

And  Catterinole.  The  very  men  who  afterward  made  the  invention 
of  the  lirst  patent  in  suit  spent  two  years  and  a  half  developing  that 
(Jattermole  process,  a  really  beautiful  id.^a.  the  lirst  process  addns-sed 
to  the  .slime  problem.    Said  Catterinole  to  himself: 

"Now,  if  I  can  have  fine  grinding  of  the  gangue  and  coarse 
grinding  of  the  metal.  I  can  separate  the  metal  out  by  its  dropping 
and  by  the  gangue  floating."  For  right  there  is  an  interesting  priri" 
.'iple  of  physics.  When  a  particle  is  floating  in  wat..r.  its  tendency  to 
sink  is  determined  partly  by  its  weight.  The  weight  tends  to  carry  it 
.lown  if  it  is  heavier  than  water.  The  surface  of  the  particle  tends 
to  resist  that,  tends  to  keep  it  up.  If  the  surface  is  greater,  in  respect 
to  the  weight,  it  will  not  go  down  so  fast.  If  the  weight  is  greater  in 
respect  to  the  surface,  it  will  go  down  faster.    Now,  if  you  imagine  a 

little  culie  of  metal  suspended  in  water,  .ti!;!  imrsir-r...-!  -.f=  !-:-...-..-.    .i: 

sions  doubled  in  all  directions,  the  surface  win  Iiave  been'squareil. 
and  that  is  the  thing  which  resists  dropping,  while  the  weight  will 


194 


TIIK    KI.OTATK'N     PKOCF.S 


Jav..  beeii  cube.!.  Tl.e  weight  l.as  inereasod  la.st.r  than  tl,.  .suMa,.*- 
llH-iv  ore  tlmt  dounl..,!  ,uh.  will  si„k  faster  throut;!,  wat.r.  That 
aw  of  the  square  as  to  the  surface,  resistiup  sinking,  and  the  cube  as 

to  the  weight  corn,,elli.,g  sinking,  is  the  thing  that  niak.s  big  pain.Ks 

drop  more  u.  aceordanee  with  their  true  speeifie  gravitv,  but  fine  par- 
leles  hke  slunes  refuse  to  obey  the  hiws  of  specific  gravity,  and  eon- 
n.ue  to  float  and  not  sinlc.  whether  they  be  mineral  or  whether  thev 

be  metal. 

As  Dr.  Liebmann  illustrated  on  the  sta.id.  if  the  rain  came  down 
in  a  shaft  it  woul.l  kiU  us  all.  When  the  «ime  amount  of  rai.,  is 
t)roKen  into  small  drops,  it  does  not  kill  us.  Whv?  Heeausc  the  stir- 
faee  has  been  so  enormously  inereas.'d  with  respect  to  tiie  wei-lit  or 
Vice  versa  the  weight  diminished  with  respect  to  the  surface  So  the 
resisting  surface  makes  those  drops  co.ne  down,  not  like  bullets  l,ut 
gently^  And  going  a  step  further,  when  the  particles  are  smaller 
s  dl,  they  will  not  com  ,iwn  at  all.  They  will  float  like  the  summer 
c-loud  m  the  sky.  Their  specific^  gra  ity  is  ju.st  as  great  as  it  ever 
was  with  respect  to  the  air.  but  they  are  .so  small  tiiat  fhev  are  floated 

The  Court:  Ts  if  because  they  are  ...  small,  or  is  it  because  of 
their  form? 

Mr.  Kkxyon:  Their  form  would  have  a  tendency  to  be  spherical 
in  all  cases,  but  it  is  a  function  of  their  size. 

TiiK  Coi,RT:     I  suppose  if  you  dropped  a  n,.,.dle  into  water  and 
kept  It  point  downward,  it  would  go  down  fiust. 

Mr.  Kenyon:  Yes.  it  would  go  right  down.  Drop  it  , sidewi.se  so 
tliat  you  have  multipli,.!  the  surface  wifhotit  changing  the  weight  and 
It  will  stay  right  fliere. 

No«-.  Caffermole  conceived  this  brilliant  idea:  If  J  can  onlv  make 
my  gangue  particles  fine,  they  will  stay  up  there  indefinitely  If  I 
••an  only  make  my  m.'tal  parti.-les  big.  they  will  drop  faster  He  knew 
lie  could  not  do  that  in  grinding.  Let  the  invcnt<,r  of  the  future  if 
he  be  here  present,  fake  this  for  a  cue:  A  grinding  machine  that"  at 
the  same  time  will  grind  the  gangue  fine  and  the  metal  coarse  will 
rcvolufioiu/e  all  these  pro,-es.ses.  raffermole  knew  that  could  not  be 
done  ,n  grinding,  so  he  said:  "I  will  grind  it  all  fine,  and  then  bv  the 
ghung  effect  of  oil.  particle  to  particle,  oil  which  g„es  to  metal  •ind 
does  not  go  to  gangue.  I  will  roll  and  work  my  metal  particles  i„tn 
big  metal  particles,  whereas  the  gangue  will  remain  as  tin.,  as  if  w,s 
ground;  and  then  when  T  have  done  that,  my  big  metal  particles  mv 
grariules.  my  spherules,  will  drop  and  the  gangue  will  go  up." 

■  :--r.:   r.  ;•„-.  i:;;-  •,  .i  i  I  rriii,  ,ir  iu.a,  rtiKi  men  propo.sed  to  do  that  thing. 


AIR-KKOTII    KIAJTATK^N — II 


Iff.') 


and  these  plaintifT.s,  and  the  world  would  have  been  concentrating 
their  ore  by  that  process  today  in  preference  ta  all  others,  probabh" 
but  tliHt  the  invention  of  the  first  patent  in  suit  was  made. 

The   Catterniole  idea  of  operation   was  by  oil   adhesiveness  and 


\yjyX*iJ-***J 


^hCkLt  H^4 


FlO.    40.      DRAWING    ACIOMPANVING    .K.    E.    CATTKRMOI.e'.S    PATENT,    >(.,    777.27.;.    „k 

PECEMDEB    13,    1904. 

nii.xing.  Air  entrainnient  was  a  trouble.  Flotation  scum  was  a  loss 
Two  to  five  per  cent  of  oil  on  the  ore  (4  to  10%  on  the  metal;  it  was 
a  rich  50%  metal  ore)  was  the  amount,  and  if  the  effects  were  dimin- 

ishin^.   then   thev   iiii^rensi'.-l    ^Jitrl-.tlv   i\...    ......... v. i    ..i?    „:: 

• ""    ■~'-5--**J'     i;-''    ;4:i':<;tw*r    »"»r    Oil.       v^iikifcCilis 

Printed  Record,  p.  212.    Q.  4.3,  44.) 


196 


■I'JIE    KI.OTATION    I'KOCKSS 


riifivuj,,,,.  a  iv.-,.s.s  wiis  taken  until  tu„  oVlo^k  i..ni.  .siiine  dav. 
liiK  CoiKT:  .Mr.  Kenyon.  I  was  wry  nuirli  interested  in  the 
ivniark  you  were  n.akin^'  h,.f,.re  recess  on  tlie  matter  (,f  tlie  dittVrenee 
iH'tween  bi!,'  parlirhs  and  little  jmrtieles,  in  the  stren^.h  of  their 
powr  to  overeoine  ivsi.stanre.  Now.  entirely  (uside  rroin  surlaee  ten- 
sion as  sueh,  and  1  mean  that  sort  of  tension  to  enable  very  minute 
partieles,  although  iiaving  a  trreater  sjieeifie  gravilv  than  other  par- 
ticles, to  float  on  the  surfaee.  Aside  from  that,  and  ashie  from  the 
•  .IS.'  in  which  the  mineral  particles  iiavin-  j^reater  speeifi,;  gravity 
are  atUiehcd  to  any  medium  of  buoyant  eharaeter  which  tends  to  sup- 
port them,  the.se  small  parthdes,  if  once  j.laccd  beneath  the  surface 
ot  the  water,  having  great.'r  sjiecifie  gravity,  of  eoui-se,  would  sink 

-Mii.  1vi:.nv,.n:  Y.'s,  ami  No.  The  ....ar.sest  will  sink  at  once.  The 
finest  ot  them  wouhl  ultimately  sink,  but  the  finest  of  them  wouhl  take 
so  long  to  .sink  that  it  is  im,.raeticabl,.  to  separate  them  or  do  anvthi,..' 
with  them  by  sinking,  and  that  was  the  slimes  prolilem  in  all"  thcie 
Mietallurgieal  operati.ms.  They  would  float  there.  Thev  would  float 
111  the  liquid.  When  y.m  get  down  to  a  certain  ultimate  i.,>int  of 
fineness,  vhether  it  i,e  metal  or  gangue.  it  will  float  in  the  water  under- 
neath the  surface. 

Tin:  ('(.iKT:     rnderneath  the  surface? 
-Ml:.  Kk.wo.n  :     I'liderneath  the  surface. 
Till-;  CoiuT:    Hut  still  they  wouhl  gradually  sink? 
Mr.  Kkxyox  :    After  a  long,  long  time. 

TiiK  Cu-KT:  [  would  like  to  underslan.l  you.  Of  course,  we  all 
know  that  if  we  could  conceiv..  a{  a  perfect  vacuum,  both  a  hiilh.f 
and  a  feather  will  go  down  together. 

Mu.  Ki:.NV„N  :  Culcr  the  law  of  tiieir  si.ecitic  gravity  ab.solutelv. 
liiK  Coi-RT:  When  you  .•oiiie.  how.'ver.  to  a  resisting  medium  (I 
do  not  care  whether  it  is  air  or  water,  then  you  have  a  different 
propusilion.  and  there  y.ai  have  a  resistance  which  has  to  be  over- 
'•"inc.  and  as  you  proc^cl  arithmetically  the  resistanc  inciva.ses  geo- 
metrically, I  believe.     Ts  that  right? 

-Mh     KiNVdn-  :       Vrs 

TiiK  CoiKT:  My  .piesti.m  is  whether  these  i)arlic|es  would  limilly 
sink.  1  want  to  get  the  theory  if  I  can.  Asi.le  from  the  .surface 
tension,  il  you  once  get  those  partieles  un.lern,>ath  the  surface  oi  the 
water,  not  attached  to  any  bubbl,.  or  any  substance  which  ha  a  less 
specitic  gravity  than  water,  will  they  not  sink,  although  at  a  greativ 
diminished  rate? 

Ar..       T.' >r.i  .,.  .     . 

-I"..    :-.r.r  ivr,  :        ;  ;;;  y  v.iii   UK  mmiciv    sink,    aitiiougil    tiieiv    IliaV    be 


ii^^ 


AIK-FROTH    FLOTATION- 


lo; 


what  they  call  a  colloidal  condition,  which   has  hccn  somc-.vhat  dis- 
cussed here— clays  arc  very  colloidal,  and  have  a  tendency  to  keep 
them  in  suspension  i)erhaps  for  days  before  they  would  sink.     Even 
they  will,  as  I  understand  it,  ultimately  sink. 
TiiK  ('(jiKT:     Ultimately? 

Mr.  Kknvox  :  The  least  little  jar  or  agitation  will  send  them  ri^'ht 
lip  ag.tm.  The  whole  slime  problem  an<l  ditficultv  in  all  metallurgical 
operations,  and  in  the  cyaniding  processes  as  well  a.s  .■onccntratio,, 
processes,  turn  just  on  the  long  length  of  time  it  takes  the  Hue 
particles  to  settle  to  the  bottom.  They  will  float  an  inch  below  tw., 
inches  below,  three  inches  below,  all  around,  almost  in<lefinit..l'- 
making  muddy  water. 

TiiK  Coi-KT:     The  very  instant  this  material  pa.'vs.'s  into  a  lar-'cr 
mesh  and  you  have  a  larger  particle,  it  will  overcome  that  resistance? 
Mr.  Kknyox:    Vcs.  sir,  and  then  the  weight  increases  by  the  cube 
whereas  the  resistance  only  inciva.ses  by  the  seiuare. 
TllK  CoiKT:     I  see. 

Mr.  Kenyon:  That  is  the  mathematical  theory  of  the  whole 
thing.  So,  the  coarser  the  grinding  the  better  these  water  separation 
processes  were,  the  greater  the  difference  in  siiecific  gravity.  But 
what  you  ran  up  against  there  was  the  fact  that  in  the  heart  of"  a  grain 
of  gangue  there  might  be  a  particle  of  metal,  and  you  have  lost  it  bv 
not  gnnding  fine.  So  th,Tc  the  millers  were  between  the  Devil  anil 
the  deep  sea. 


Mr.  Kenyon  :  It  has  been  shown  that  the  processes  of  the  patents 
ui  suit  depeud  in  part  at  least  upon  certain  simple  facts  of  phvsical 
science  that  are  observable  to  the  knowing  eye.  an<l  that  clearlv  .lis- 
tmguish  them  from  the  prior  art.  We  have  shown  that  these  pro'ces.ses 
are  not  oil-foam  or  oil-froth  proces,ses.  or  oil-emulsion  i)r..ccsses.  or 
aerated  oil-flotation  processes  in  any  proper  sense,  but  an-  pro<.esses 
of  air-flotation:  processes  that  effectively  evoke  the  power  of  air  to 
s.'lect  out  the  metal  from  the  gangu.'  in  a  freely  flowing  pulp,  and  to 
float  It  to  and  through  the  surface  for  separation. 

Air  has  little  affinity  for  oil  as  such,  and  air-bubbles  do  not  rcadilv 
attach  themselves  to  oil  globules,  and  liave  slight  lifting  power  whei, 
so  attached.  If  a  particle  of  mineral  lies  entrapped  in  an  oil  globule 
or  has  an  oil  globule  attached  to  it,  an  air  bubble  coming  in  contact 
with  the  oil  globule  will  take  away  a  portion  of  tho  oil.  I.nt  «i!!  h.-.- 
little  tendency  to  attach  itself  to  the  mineral.  Th.Tefore.  while  air 
bubbles  may  be  mechanically  caught  and  entrapped  in  oil.  and  mav 


l!».s 


TllK    FLOTATION    PKoci-ss 


th       nay    .ncvas.  and  gr.a.ly  in,.,.,a.e  tl.e  ma«s  buoyancy  of  the 
'.  >''.  t  IS,  Its  power  to  rais,.  mineral  particles  that  arc  also  caught 

?  s„  ,1  ,„  the  0,1-  oan.  processes  of  the  prior  art)  is  not  securcl  unle:s 
'"■  ;'-""    '"  -.l  ..s  surticient  and  the  character  of  oil  suitahle  to  so 
MH-hanu-aliy  cnhraee  and  entrap  ho,h  air  and  mineral.     That  is   the 
oil  iinist  be  vjseous. 

Air  has  a  powerful  affinity  for  clean,  n.etallic,  sulphi.ie  surfaces 

ns  aftunty  .  defeated  for  all  practical  ore  concentition  purpl^!^ 

en    1  when  the  nnneral  surfaces  are  coated  with  so  nu.ch  'l  as 

to  exh  h,t  ,hc  physical  properties  of  oil  as  such,  such  as  adhesion  ,0 

other  sundar  oded  nuneral  surfaces,  as  in  the  Catterm.le  proces.s   or 

<  herence  to  an  od  lake  or  to  an  oil  foam  mass  and  resuUant  huoy- 

.    '-     rtotat.on,    as    m    the    Elmore    process,    the    CaHf.rnu,    Journal 

aocess,  and  so    orth.     Hut  when  the  filn.  of  oil  on  the  metallic  sur- 

it'ZTT^  f  "r'  ^''  "'""  "^'  ''  °''  *"  "-  -  -"P'--i) 
sii  V       'i        ""■   r  V  ''  ""  '""■^'■•^  "-lefeated;  it  seen.s  to  be 
1-situeh   „,crease,l   (why.  we  do  not  know)  so  that  for  all  praeti..al 
oro  concentration  purposes  in  the  nnll  the  attachment  will  perJ  J 
"".1  out  01  t],e  pulp,  and  will  survive  any  a.nount  of  e.xces,s -...itatio 
or  of  excels  aeration  in  the  pulp.  'i^irauon 

Air  bubbles  have  vastly  ,M-eater  lifting  power  for  metal  particles 
t  an  oil  .lobules  have,  and  especially  the  sort  of  air  bubbles  that  are 
pioduc^ed,  either  by  a,^itation  or  by  aeration.  i„  water  modified  bv  the 
reagents  ot  the  patents  in  suit.  • 

Air  bubbles  in  unmoditied  water,  however  produced,  pro.re.ssivelv 
an.l  rapid  y  codesce.  and  with  explosive  violence,  which  tends  to  ex- 
pl.  in  the  fact  that  such  air  bubbles,  namely  i„  unmo.lif.ed  water  u  Ml 
not  practically  concentrate  ore. 

suitHi'vI"'!''''"'.'"  '",''  :"""'"^  '•'■  ''"■  ''''""''''  °f  the  patents  in 
suit  ha^e  an  enhanced  .selectnv  affinity  for  metal  over  jran^e  (whv 
-e  do  not  know),  ami  a  persistence  of  l.fe  as  bubbles  i„  the  pulp 
and  a  P--tence  of  attachment  to  contacting  metal  particles  in':;;! 
'">'  -:  the  pulp  sufl.cent  (but  why.  again,  we  do  not  know)  to 
pcnn,  ,n  pnictice  of  ready  separation  and  removal,  and  to  resu 
flieieh\   in  cfTective  ore  construction. 

Tin:  CorHT:     You  say  "AVhy.  we  do  not  know."     Is  there  anv 
theory  on  tliat  subject?  • 

-Mr.  KK.NYf)N :    We  have  presented  no  theory. 

The  Court:    You  have  no  theory? 

>rFt.  Kexyhn.     We  have  no  theory.     Dr.  Sadtler  says  variation 


AIR-FlioTII    II.OTATION-- 


l!)l) 


,in  not  t  ""T"  '"'"""  ''"■  "''-'—"'  '"'t  I'-v  '  .io  not  know. 
I  do  iot  know  how  variation  of  surla.-,.  tension  can  enhance  sc-lective 
.  ftnit^y  or  how  it  can  cxphiin  persistence  of  life  as  bubbles  in  an,] 
"Ut  of  the  pulp  or  how  .t  can  explain  persistence  of  attachment  to 
-n  acting  >nctal  par,i,-les  in  and  out  of  tl.e  pulp,  to  such  a  degree 
that  practical  ore  concentration  in  a  mill  is  an  ac  oniplished  fact 

Whatever  the  explanation  of  the  phenomena  invo.ved,  it  is  clear 
that  the  operation  proceeds  by  cc:.tact  of  air  and  metal  in  a  freelv 
flowing  pulp   under  circumst.n.ces   conditione  1    .v   tl-     presenc   Jf 

n.n.H'11*."'""'  '     ^''"  '"•■  ""■  '■""""•'  ^''''''''  ^''"'  ''''  «'"'  "'^  "li-H^ral 

J'<*1  IJi.  its  . 

Ml«.  Kkwox:     1,1  thf  pulj), 

T,iE  (V.rRT:     Xow    if  the  mineral  particle  has  a  rilm  of  oil.  no 
atter  how    hin.  how  is  there  any  actual  physical  contact  between 
the  an-  .nid  that  ])article? 

Mp_  Kexvox:  The  mystery  of  the  thing  is  that  when  the  oil 
fil.n  ot  the  attenuated  character  that  is  produced  with  one-tenth  of 
,  ot  od  to  the  ore.  when  that  film  is  present  on  the  metal  particle 
t  -  au-part„.|e  has  .,n  enhanced  appetite  for  it.  seeks  it  with  iiLeased 
aA.dit.v.  instead  of  with  diminished  or  defeated  aviditv  such  as  a 
ttncker  him  will  produce. 

Thf  CocRT:     And  it  .seeks  it  through  that  very  thin  film" 

that  hel,  s'''"'^'^    ■'''''''  '^  """""^''  ^'^'^  '■'■'•■  *''■"  ^^'"'  ««  •*  ^^•"'•''~ 

Tmk  CorRi  :  Not  through  the  actual  co.tact.  but  through  the 
film  l,eing  so  very  attenuated,  it  seeks  the  metal  particle,  and  the 
n.'erpoMt.on  ot  the  film,  far  from  lessening  the  s.^ctive  a..tion  of 
llie  air  tor  the  metal,  enhances  it— is  that  n>'ht' 

Mn.  Kexvox:     Yes.  that  is  right,  and  Dr.  Sadtler  on  the  stand 
uggos  e.   an  Idea  tha^  may  help  a  little.    He  said  that  an  attenua 
"''"•'t   that   kind   might  po.sibly  be  concived  of  as  smoothing 
roughness  ot   the  surface  of  .Lavage  of  the  .sulphide  particles 

Mr.  A\ii,li.\ms:     That  was  Dr.  Liebmann. 

AFk,  Kexyox  :    Dr.  Liebmann  ? 

Tiif:  Court :     Increasing  the  eflfect? 

Vnf  n,^T'''!r      I"7<'«''*i"P   the   attachment   or  appetite   of   the 
a,r  bubble  for  that  surface  .so  smoothed. 


\1t>   ^v, 


y  iV.iii  suggested  it. 


Mr.  Kexvon:     Yes.  Dr.  Liebmann  also  suggested  that  idea:  and 


200 


■l.Ih;    Kl.lir  ATION     l'K(ICE;sb 


Mr.  l)osri:liilcli,  MS  I  i-fiiiciiiliiT.  siiiii  tliiit  wlicii  tlirsi'  |mrtli-lcs  IiikI 
roti^li  siirfai-fs  the  iiir  Imhlilr  would  not  liolil  tliciii.  Tt  is  the  siiiootli 
siirt'aci'  that  tlif  air  hiilililf  j;t'ts  its  ^rip  on.  Now.  tliis  iiiicroscopn; 
tiliii  of  oil  may  lill  up  inii'roscopic  cavities.  iiia\  l)ri(it;i'  over  niii-ro- 
scopic  rou<;liiit'ss«'s.  may  make  smooth  wiiat  was  hi't'orc  I'ouijh.  aiul 
ill  tluit  way  cuhauci'  tiio  avidity  ol'  tho  aii'  pai'titdc  for  it,  and  the 
•rrip  of  the  air  particle  u])oii  it;  liut  I  present  that  uith  ditlideiice. 
That   is  a  matter'  of  speculation. 


T.y9 


Fk;.     41.       TilK    (JAHHKTi     SlIXKTl. 


KFm(  Kl)    lACSIMlI.K   Cll-   DRAWING    IN    K.    B.    GAnnKTT's    PATKNT    No.     H  l.:U.'. 

.lAMARV    G.    1S91. 


UK-rHOTlI    Kr,OT\TI(l.\- 


201 


TllK  ('(iritT:  V(i\i  have  tlic  uvidriiec  on  liolli  sides  lor  that,  sii  1 
dii  not  siipposf  coiiiisi'l  on  cither  si(h'  will  contest  it. 

-Mh.  Kknvmn:  Tliat  is  .so.  hut  witii  all  rcsjicet  to  hoth  witnesses. 
I  present  till'  siitrjicsiion  with  dilVidencc, 

Hut  now  let  nic  state  atrain  what  arc  tin'  clear  essentials  I'roni 
tile  point  of  view  of  operation,  whatever  the  explanation  of  piienon.ena. 
Whatever  the  explanation  of  the  plienomena  involved,  it  is  clear 
tiiat  the  operation  proceeds  liy  the  contact  of  air  and  metal  in  a 
freely  flowing'  P"lp  under  circumstances  conditioned  by  the  presence 
of  the  rcatrents  of  the  patents  in  suit,  and  ojjiiortunity  of  flotation 
after  contaet.  Vou  have  trot  to  l)rintr  your  1)ul)hlo  and  your  nietal 
particle  into  contact  in  this  freely  flowinjr  pulp,  and  under  circiun- 
staiiecs  conditioned  by  the  i)ri'sence  of  the  rea|;eiits  of  the  i)atents 
in  suit.  l-!ut  to  have  liroufrht  them  into  contact — that  is  not  onoujrh. 
There  must  he  another  factor,  namely,  opportunity  of  Hotatiou  after 
contact,  .so  that  you  may  separate — flotation  uj)  in  the  pulp  and 
throusrh  (he  surface  of  the  pulp — so  that  you  may  practically 
sc])arate  them. 

Tn:;  Corirr:     'i'hose  iirt>  essentials  in  the  flotation. 

Mi;.  Kknyon:  Those  are  the  sine  qua  nornt,  and  those  are  the 
only  sim:  qua  lums  if  we  have  presented  the  projM'r  theory  of  operation. 

And  as  to  apparatus,  it  is  clear,  loo.  that  apparatus  for  erticicney 
bringring  about  iii  a  freely  flowing  pulp  the  contact  of  air  and  metal 
under  the  conditions  stated,  and  for  permittin<r  or  assistinjr  flotation 
after  contact,  is  all  that  is  required. 

It  has  been  shown  not  only  that  the  tine  and  slime  that  wt>re 
inactically  imconcentratable  in  the  prior  art.  except  perhaps  by 
Cattermole — I  say  'perhaps'  because  Cattermolc  never  reached  the 
mill.  On  the  threshold  of  the  mill  the  life  of  the  (^attermolc  process 
was  cut  otT  by  this  prreater  child  of  the  brains  of  Sulman.  i'icard. 
and  Uallot. 

It  has  been  shown  not  oidy  that  the  fine  and  slime  that  were 
practically  unconcentratable  in  the  prior  art  (except  perhaps  by 
rattermole  can  be  succepsftilly  concentrated  by  the  proces.ses  in 
suit,  but  also  that  the  presence  of  such  fine  and  slime  in  the  pulp 
actually  assists  the  concentration  of  the  ore.  and  is  indeed  almost 
cs,scntial  to  practical  success;  so  much  so  thai  the  art  of  grinding 
has  b.'cn  revolutionized  where  the  processes  in  suit  are  employed 
and  line  Kriniiing  lias  become  itie  rule,  wiiere  before  it  would  have 
been  the  ruin,  of  the  mill. 

The  history  of  what   happened   in   the  practical   art   before   the 


n 


'J(I2 


■rrii:  ki.utation   i'imci;: 


iiivfiitidiis  111  suit  wfiT  iiiadc.  ami  of  wliat  lui.s  liapju'iir,!  in  th,- 
prartiral  art  Niiiic  tl.at  time,  shows  tiiat  wliilo  ways  and  incaiis  of 
I'l-infjin-;  alioiit  imita -t  of  air  ami  metal  in  the  pulp  and  of  jjcrmittiiif; 
or  iLssistinj.'  Hotatioii  after  eoiil:iet  may  he  wiilely  varied,  the  success 
'  '■  the  ])r;ii'ess  is  sharply  eomlitioned  witliiii  relatively  narrow  limits 
ill  Ihe  matter  of  the  f|iiantity  of  reaffeiit  employed,  when  that  reag;eiit 
is  the  oil  of  the  tirst  jialeiit.  Ksperially  is  this  true  and  crucial  in  the 
ease  fif  the  lirst  patent  in  suit,  since  it  has  heeii  <leiiioiistrated  heyond 
disjiute  that   any  notahle  increases  of  oil  ahove  the  minute   juvipor- 

tioii   there  specilied   practically  defeats  tl iid   in    view   and   would 

in  the  mill  i)raetically  prevent  the  c eiitratioii  desired,  and  woiihl 

he,  not  only  intolcrahle.  as  a  dirty  and  utterly  noii-coiit  rolhilile  mill 
oi)eration,  hut  imjjossihle,  as  ■;ivii|ir  at  jxreatly  enhanced  cust  a  j.'reatly 
dei)lete(l  and  inferior  product. 

Now,  why  the  liuhhles  have  enhanced  selective  aflinity  foi'  metal 
over  L'anirue.  and  why  they  lun  ■  enhanced  jiersisteiicc  of  liiV  as 
hiilihles  in  and  out  of  the  jiulp.  no  one  i-eally  knows.  No  one 
really  understands  today  why  the  process  works  as  it  does  work. 
I  iider  such  cii-cuiiistanees  jiri'vision  was  impossihlc  A  id  where 
prevision  is  imiiossihle,  nothiiif^  can  anticipate  except  the  very  thiiifr. 

TiiK  CoriiT:  That  would  indicate  that  this  was  a  discovery 
rathei'  tlian  an  invention  of  a  jtroccss. 

Mn.  Ki;.\vn\:  Yes.  It  started  with  a  discovei'y.  As  a  jirncess  it 
1 ame  an  invention. 


CYAMDK    TKI;aTMK.\T    ok    flotation    CONCKNTIiATi: 


.'(i:! 


CYANIDE  TREATMENT  OF  FLOTATION  CONCENTRATE 

Hy  (,'iiAHi,E.s  Blttkk.s  and  J.  E.  ('i,knni:i,i, 

IFroiii  the  Miiniin  anil  Siii  ntific  Pnns  o|  Xovfinlicr  L'O,  r.il.'.i 

W1k-ii  ('liiirl.s  Huttcrs  l)if.MM  to  take  iij)  fh,.  wmk  of  Holatioii 
ill  our  Oaklaiiil  lalioratory.  oiiu  of  tlie  tirsi  i)oiius  l)roiii,'l:t  to  our 
attention  was  tlie  troatinnit  of  tlie  eoiici'ntrato  proiluced  })y  flotation: 
J.  K.  CkMincll  was  accordinfjly  instruL-tcd  to  undertakf  tiiu  n-.Sfarclifs 
detailed  in  tiie  present  pa{)er. 

The  whole  value  of  the  i)ri(eess  hinfjes  on  two  points,  namely, 
tile  iiviulr  ,,f  tailing'  produeed  and  the  net  realization  of  the  value 
L'ontained  in  the  eoneeutrate,  these  two  eonsiderations  liein^  of 
equal  iiiiportanee.  This  last  point  is  coniplieated  hy  (pustions  of 
treoirraphieal  situation,  for  if  the  eoneentrate  eaiinot  be  treated  locally 
the  eost  of  realization  may  lie  so  heavy  that  flotation  would  he  entirely 
precluded. 

The  results  obtained  in  our  laboratory  by  the  eoiril)inatioii  of 
flotation  and  cyanide  have  been  so  remarkable  that  a  serious  study 
of  the  disposal  of  concentrate.s  has  been  forced  upon  us. 

The  ditliculties  attendinpr  the  treatment  of  eoneentrate  by  cyanide 
aie  well  known.  The  i)rocess  of  eonecntration  collects  in  a  small 
bulk  not  oidy  the  valuable  <-()nstitutents  of  the  ore  but  also  those 
substances  that  act  as  eyanieides,  or  which  are  readily  converted 
by  oxidation  or  otherwise  into  cyanicidi's,  so  that  their  influence, 
per  ton  of  material  treated,  is  <rreater  than  would  be  the  case  with 
the  unconeentrated  ore.  Ileavy  minerals  such  as  the  sulphides  of 
iron,  copper,  lead,  arsenic,  antimony,  zine.  and  double  .sulphides  such 
as  mispiekel,  proustite,  ])yrarsryrite.  and  bornite,  naturally  tend  to 
accuniub'te  in  the  concentrate.  If  some  interval  elapses  between  the 
formation  of  this  concentrate  and  its  treatment,  oxidation  nuiy  take 
place,  with  formation  of  sulphates,  arsenates,  and  antimonates.  whicli 
are  still  more  detrimental  to  c.vanide  treatment  than  tie  orirrinal 
minerals.  These  ditliculties  have  been  wholly  or  partly  overcome 
by  the  adoption  of  modifications  in  the  treatment,  such  as  preliminary 
water,  acid,  or  alka.i  wa.shinpr,  roast  in?,  fine  prindinfr,  the  use  of 
special  solvents,  such  as  bromo-eyanide,  and  pn>lonped  contact  of 
the  material  with  cvanide.  extendiiiir  in  some  case.';  to  over  n  iii.infV. 

In  the  case  of  eoneentrate  produeed  by  flotation,  the  minerals 
eomposinof  the  product  are  substantially  the  same  as  those  obtained 
by    rrravity   concentration,    consistinpr   of   the   sulphides   and    double 


<l 


♦  _ 


204 


Tiih;  ri.nivnuN   ruKCF.ss 


Mllpliitli'S  of  till-  hrii\\'  mrtiils.  aiid  it  is  Id  he  f.\|KM-|cil  llijit  tilt' 
saiiic  (litlii'iiltics  «ill  he  ciicdiiiitcrcd  in  their  trcjitiiifril.  Hut  as  the 
coiirtiitiati'  also  contains  a  lonsidii'alilc  part  of  tlic  oil,  tar.  or 
other  flotation  aj^'ent,  the  pi-esenee  of  tiiis  toreijin  iiiattei'  nnisl  he 
taken  into  aeeoiint.  In  some  eases,  this  eireniiistanee  iiitro(hiees  an 
additional  ditTieidty.  A  part  of  this  oi-jjanie  matter  is  sohihh'  in  tiie 
eyanide  or  alkali  used  in  the  jiroeess.  and  the  solution  so  forni'il 
may  he  eapal)lt'  of  ahsorhinu  oxytjeii.  The  etVeet  produeed  hy  ear- 
bonaeeoiis  matter  in  prcfipitating  ^olil  and  silver  pi'evionslv  rlissohcd 
hy  eyanide  is  well  known  and  has  Imtu  a  .sonree  of  nnieji  trmihle  in 
many  loealities.  Some  of  the  constituents  of  this  nuittcr  are  not 
ciusily  eliminated  and  apjxar  to  icsist  oxidation  even  at  a  hitrli 
teniperatuiv ;  roastinj;  under'  ordinary  conditions  does  not  completely 
remove  the  carhon  ;  it  is  prohahle  that  a  portion  derived  froni  tar 
remains  in  the  irrai)hitic  form.  cai)ahli'  of  acting  as  a  precipitant  for 
irold  or  silver. 

The  exi)erimen1s  detailed  helow  uer'c  made  on  concentrates  pro- 
thiced  from  typical  frold  and  silver  ores  liy  a  modified  type  of  the 
Minerals  Separation  tiotation  machine.  Most  of  the  tests  were  made 
in  netdral  or  alkaline  media.  The  frothing;  agents  emi)loyed  were 
those  in  general  use.  consisting  of  tar,  creo.sote.  carbolic  acid,  pine-oil. 
and  fuel-oil.  ll  is  not  proposed  to  discuss  these  in  detail  in  the 
present  paper:  it  will  he  suflicient  to  state  that  the  concentrate  was 
collected  and  drained  on  a  vaeuum-tiltcr  and  in  some  cases  dried 
at  a  moderate  temi)erature  hcfoi-e  treatment. 

As  an  example  of  an  ore  in  which  the  value  ccuisists  essentially 
of  gold  we  may  take  the  product  of  the  San  Sebastian  mine,  in 
Salvador,  operated  by  the  liutters  Salvador  Mines.  I^td.  For  ju'e- 
liminary  work  a  composite  si',mi)le  wiis  ma(h'  from  21  lots  taken 
fi'om  different  jvai'ts  <if  the  mine,  and  conceiiti-ate  produced  by 
treating  the  linely  crushed  oi-c  in  a  ]()-ll).  flotation  machine.  The 
sample  taken  for  this  test  as.sayed  originally  l.;'J4  oz.  gold  and  0.28  oz. 
silver.  The  concentrate  obtained  by  flotation  assayed  4.02  oz.  gold 
and  1.14  oz.  silver.  As  this  cf)iistituted  2t')'J'',-  of  the  weight  of  ore 
taken,  the  gold  recovered  in  the  concentrate  amounted  to  70.0%  of 
the  total.     An  analysis  of  the  concentrate  showed : 

%  % 

Insoluble    44.3       Iron   24..1 


together  with  small  (luantities  of  molybdenum,  tellurium,  and  other 
olements.     The  tailing  carried  0.04  oz.  gold  per  ton. 


CVWfhK    IKKVTMKNr    (»K    ll.o'lA  TIoN    fONCKNTKA  11. 


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'I'lii'  lif.st  t.'sls  wriT  iiiaili'  uilli  ihr  olijiMt  (it'  ilfliTiniiiiii^'  wljcthrr 
llii>s  iiiiilfrial  cimiM  Im'  trciilcd  a<lvaiilaKC(Mi.sly  raw  liy  a^'itatiori  with 
cvanidf.  Ill  adiiitioii  to  .lir.'ct  cyaiiiilv  trcatiiiciil  various  iiioditica. 
lions  urr.'  tiiiil.  as  shown  in  TaMr  I.  iiirludin^;  a.ldilioii  of  Icail 
airtatr,  pnliiiiiiiary  alkali  tiialin.Mit.  ilisiil[)liiiri/iiijf  with  alkali  and 
aliiiiiiimiii,  ami  hronio  cyaiiidc  Tin'  last  i.roccdurc  showed  a  iiiark.'d 
iiiiim.'  •iiifiit  over  evrry  otlur  nifthoil  of  raw  t  realiiicnt.  Iml  still 
failed  to  yield  a  satisfai'tory  extraction.  The  extniction  was  inereased 
hy  inereasiiit;  cyanide  strenj;th,  hut  with  strong'  solution  the  coii- 
.simiption  of  cyanide  hecanie  prohihitive,  and  alkaline  siiliiliides  were 
tiiriiicd.  This  elVcct  can  he  prevented  and  cyanide  lonsuiiiption 
much  rdiiced  hy  addition  of  lead  acftate.  some  im|.roveincnt  in 
extraction  heint;  ol.iiiined.  Preliminary  alkali  trcat'iiciit  with  or 
without  all.  linum  showed  ni>  henclit  whatever.  The  fact  that  hroino- 
cyanide  has  a  marked  itTcct  on  the  extraction  sujrjrests  that  a  portion 
of  the  u'olil  may  he  |, resent  as  a  tcllurid.'.  This  conclusion  is  supported 
hy  experiments  made  liy  direct  treatment  of  the  orifrinal  oro,  without 
concentration;   these  tests  showed   that    a   certain    i)ro|)ortion   of  the 

>-'"'''    '^   i'l'" ssihlc   to   cyanide   even    after    very    line   ffrindiiif,'   and 

prolonged  contact.     (See  Tahle  XI.) 

As  these  results  did  nut  appear  cncourajrinji  for  any  system  of 
raw  treatment,  attention  wjis  next  turned  to  roastiiip.  It  was  soon 
found  that  roa.stinj;  within  certain  limits  of  temperature  converted 
a  consideralile  part  of  tlie  copper  into  sulphate,  which  could  be 
leached  with  water,  tofjether  with  some  .sulphate  of  iron,  leaving'  the 
lesicliie  ill  a  favoratile  conditir»n  foe  \vanide  treatment.  Preliminary 
acid  wasli  of  the  roa.stcd  material  was  also  tried;  thi.s  would  have 
the  adv.-iiitair.'  of  dissolvini:  a  further  (piantity  of  copper  that  mi-rht 
have  hecome  converted  into  oxide  in  the  roa.stiiipr,  hut  the  results 
show  that  the  benefit  obtained  would  not  warrant  tli(>  additional  cost. 
Another  test  was  made  in  which  the  concentrate  was  cyanided  raw 
1"  forc'  roastinj,'  aii.l  acid-wa.shintr,  and  re-eyanided  after  the  wasliitijr 
tills  also  showed  no  advaiitaire  either  in  extraction  or  cy.-inide  eoii- 
sumption  over  direct  roast  ins:,  water- wash,  and  cyanide.  In  all  Ci-scs 
the  roasted  material  was  ajritatd  with  cyanide,  using  a  dilution 
of  ;^;1.  Th.'  results  obtained  by  tiie.s<>  three  methods  are  shown  in 
the  followiiitr  table.      fXo.  11.^ 

In  Test  No.  2  the  aeiil-wnshinff  was  made  with  1^  II.SO,.  usinp 
approximately"  n  tons  of  wnsli  nor  tnii  of  enneenir.Tte  tre.-.f^j.l  T'..--?.-.-.-. 
agitation  with  cyanide,  the  pulp  was  re-ground  in  a  model  tube-mill 
with  glass  marbles. 


CYAMDt    TKKATMKNT    OK    KU)T.\T|UN    (DNC  K.NTKATi; 


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In  Test  No.  .'}  tlie  preliiiiiiiary  raw  treatiru'iit  was  made  witli 
0.1%  KCN  iisiug  a  dilution  of  12:1,  for  two  days;  the  extraction 
of  gold  was  12%.  Aeid  tnatiiient  was  made  with  1%  ILSO^, 
dilution  1:1,  agitated  IS  liours,  and  then  leaehcd  with  water  before 
eyanidiug.  Roasted  and  washed  concentrate  agitated  with  cyanide 
lor  i  days. 

Test  No.  1  on  Tal)le  II  indicates  tiiat  tlie  flotation  concentrate 
from  the  San  Sebastian  ore  may  be  successfully  treat. 'd  by  a  siini)l(' 
process  of  roasting,  water-washing,  and  cyaiiiding.  This  conclusion 
was  confirmed  by  numerous  experiments  on  a  large  scale  in  which 
the  material  was  roasted  in  a  haiul-reverbcratory  furnace,  and  the 
roasted  product  trea'rd  by  agitation  in  tanks  with  mechanical 
stirrers,  adding  water,  .^'ttling.  and  decanting  until  the  bulk  o  the 
copper  and  iron  salts  was  removed,  finally  collecting  the  mat.'rial 
on  a  vacuum-filter  ami  wa.shing  on  the  filter  to  retmive  the  last 
traces  of  soluble  siilts.  The  washed  concentrate  was  then  re-pulped 
with  lime  and  cyanide  solution  in  ai  agitation-tank,  and  treatment 
continued  in  the  ordinary  way.  Tlie  results  of  the  bottle  tests  were 
fully  confirmed. 

Attempts  to  treat  the  material  by  percolation  were  not  successful. 
Owing  to  the  fine  grinding  of  the  ore  previous  to  flotation,  the  roa.sted 
material  showed  a  tendency  to  slime;  percolation  took  j)lace  slowly 
and  irregularly,  through  chainiels  formed  in  the  ma.ss.  .so  that  the 
extraction  by  this  means  was  always  imperfect. 

In  the  tests  made  in  the  larsre  muffle  the  oxidation  was  somewhat 
more  effective,  but  a  rather  longer  time  was  re(,iiire(i  to  reach  tiie 
temperature  a-  whii'h  roasting  began.  Tempi  ratiire  was  approxi- 
mately determini'd  by  Seger  cones. 

On  examining  the  details  of  Table  III.  it  will  be  apparent  tiiat 
the  most  favorjible  re.sults  were  obtained  when  roa.sting  was  carried 
out  at  a  low  temperature;  under  these  conditions  a  maxinnun  amount 
of  <-opper  was  extracted  by  water-washing,  an.'  the  hitrhest  extraction 
of  gold  obtain.'d   with  a  niiniitium  cyanide  consumption, 

Tn  this  ore  the  silver  is  neprlifrible.  but  it  is  signifi<-ant  that  tiie 
silver  cxtrMition  on  the  roasted  material  is  poor  in  all  eases.  This 
condition  will  be  noted  in  most  cases  wh(>re  attempts  have  been  made 
to  tre;it  silver  ores  by  cyatiide  after  an  oxidizing  roast. 

With  these  results  as  a  guide,  tests  were  made  on  a  larger  seale 
on   fhe  same  material,  roasted  by  band   in  an  oil-fired  reverberatoi-y 

I'urnaee,       .\    ehaT'Cre    of   about    400    11)     w;is    d.rjed    slow'v    in    ;;    ';;i!e.:-.!: 
drier,  and  charged   into  the   furnace:  the  temperature  was  frradnall\ 


J 


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raised  till  it  approxiiiiutt'il  tiuit  obtained  in  tlu'  iimffle-roasts.  jirolialily 
alioul  550°  C.  After  .'{i  hours,  the  tiaiiie  was  turned  off  and  the 
charge  allowed  '  cool  in  the  t'urnaee  over-night.  The  eoiieentrate 
roasted  in  this  way.  showed  little  or  no  tendency  to  sinter  or  form 
lumps,  hut  in  suhstMiuent  tests  when  tlie  material  was  charged  without 
previous  drying,  {)ortions  of  the  concentrate  agglomerated  into  com- 
paratively hard  lum]>s,  which  contained  a  core  of  unroasted  material, 
and  which  it  was  necessary  to  sift  out  and  re-roa.st  after  grinding. 
Possibly  in  praeiice  it  would  he  advisable  to  j)ass  the  material,  after 
lirying  and  before  roasting,  through  a  ball-mill  or  similar  |)ulveri/er. 

A  bottle-test  made  on  a  scale  of  100  gm.  on  a  sjimple  of  roasted 
concentrate  from  the  above  i'cverb(>ra1ory  charge  showed  the  following 
results: 

T.ABI.K  IV 

Copiier  extracted  iier  cent  of  raw  concentrate: 

By  water-wash   0,435 

B.v  cyanide    0.039 

Total    0.47-1 

Cyanide  consumed  |ier  ton  of  washed  concentrate 5.03  lb. 

Cyanide  consumed  per  ton  of  raw  concentrate 4.21  lb. 

Under  cyanide  treatment   3  days 

1  ton  raw  concentrate  ==0.837  ton  washed. 

Gold.  Silver. 

Oz.  Oz. 

Assay  of  roasted  concentrate  3.70  0.86 

-Assay  of  washed  concentrate   3.90  0.94 

Assay  of  washed  concentrate  caNiiUittd  on  raw  coiircMtraic  3.2ti  0.79 

Tx)ss  jier  ton  of  raw  concentrate 0.24  0.10 

Residue  assay  on  washed  concentrate 0.05  O.tiO 

Residue  assay  calculated  on  raw  concentrate 0.04  0.50 

Kxtraction  on  loanted  and  wa-shed  concentrate 9^.7  36.2 

Kxtraction  calculated  on  raw  concentrate 9S.9  43.8 

Recovery  calculated  on  raw  concentrate 92.0  32.6 

The  loss  shown  in  this  test  seeiris  to  be  mostly  meciiani<'al.  due 
to  dust  carried  off  while  stirring  the  charge:  it  could  probably  lie 
much  reduced  by  using  a  suitable  roa.stt>r  with  revolving  rabbles  and 
a  dust-chamber. 

AoiTATKiN  Tests 

The  following  tests  were  made  in  small  tanks  fitted  with  wooden 
paddles. 

No.  1.    Agitated  with  cold  water,  washed  by  settlement  and  decan- 


212 


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llll;    FI.OTAIIDN     I'KilCKSS 


tatidii,  then  (Iriiiiifd  liy  vanuiiii  on  u  licrizoiital  liltcr-lia.v ;  rc-piilpcd 
witli  lime  iiiicl  cyiiiiidf  solution. 

No.  2.  Afjilatcd  witli  hot  water,  ua.slic.l  hy  .sottlcnu-iit  and  dccaii- 
talioii,  ii.Mitiali/.fd  witli  liiiu-  and  .liritatcd  with  cyanide  witiiout 
l>revioiis  filtration.  Cyanide  treatment  hy  ileeantation,  finally  washing 
without   water. 

l'i;K((ii.\ri().\   Tksts 

TortioiLs  of  till,  siinie  roasted  charKe  as  were  u.sed  for  the  previoii.s 
tests  w.'ro  leaehed  in  tanks  with  a  canvas  tilfcr.  usin-,'  vacnnni  to 
anl  filtration.  After  wa.shi-ij;  out  .soluble  .salts  as  far  as  possible  in 
this  way,  the  residue  was  i  li.xcd  with  lime  and  tieafed  by  i)ercolation 
with  cyanide  .solution  in  the  same  mainier. 

In  view  of  the  un.satisfaetory  results  obtained  by  percolation  and 
the  tact  that  further  extract  ion  was  made  by  increased  water-wiushins,'. 
the  residue  of  charge  No.  1  was  mixed  with  the  residue  oT  eharsre 
No.  1  treated  by  atritation  sec  Table  Vi  and  the  united  char^'e 
HKitated  further  with  water,  then  with  weak  cyiuiide  solution  and 
filially  with   water  ajrain. 

The  result  of  tliese  te.sts  indicates  that  tl]orou<rh  washing;  is  e.s.sential 
foi-  a  liii,'h  extraction.  l''iltrafion  without  vacuinn  was  found  to  be 
]>ractically   impossible 

The  followinjr  tests  were  made  on  another  portion  of  roasted 
concentrate,  to  determine  the  influence  of  cyanide  sfren>rtli  on 
extraction.  Hijrht  tests  were  made:  in  the  lirsf  four  a  preliminary 
wash  was  given  with  hot  salt  solution.  1(1','  XaCl  usiiifj  2  tons  of 
material  treated.  In  the  remaininsr  four  tests  the  imliminarv  wash 
was  given  with  water  alone,  u.sing  4  tons  ])er  ton  (d'  material.  The 
salt  wa.sh  showed  some  extraction  of  silver,  but  it  does  not  appear 
tliat  any  advantage  derivecl  from  this  would  warraid  the  additional 
cost. 

The  eyainde  treatment  is  detailed  in  the  accompanying  tables: 

From  these  results  it  ap  'mi-s  that  the  extraction  is  scarcely 
aflfeeted  by  variation  of  cyanid.  itrcngth  within  the  limits  and  under 
the  conditions  of  the  tests.  The  cyanide  consumption,  however, 
iiicrea-ses  with  increasing  strength.  Ai>pareiitly  tlie  best  results  are 
obtained  with  a  .strength  of  OA'I')^',    K("X. 

Two  tests  were  also  made  on  another  portion  of  roasted  concen- 
trate from  the  same  lot   of  ore  to  determine   tlii'   influence  of  time 

From  this  test  it  is  evident  that  the  gold  in  the  roasted  concen- 
trate  is   rapidly  soluble    in    cyanide.      The   small    insoluble    portion 


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■'III;    H.OI\l|()\    PKOCEHS 

M'..iMs  t.,  I,..  ,|uit.-  ir,iUT...s,sil,|,.  to  pn.hm^T,!  tivalm.Mt  „r  t,,  str„„.',.r 
solulimis. 

Th.  foivsroiM^f  trsls  Mitli,i..,ill.v  iM.i.,-;,!.-  iliat  til,.  San  S,.i.H.stia.i 
'•"■"•••"tntt...  ,,ro,lu,...,l  |,y  tlotali,,,,,  ,„,.y  („■  ,,vat,.,l  su,v,  -  ,.„||v  „,, 
11  .•oninicirial  hasis  \n  t|„.  „,..t|,o.l  .,f  r.r.usUu^.  wat.T  uashuitr  '  a,ul 
.■WiMi,l,ntr.  S,„„,.  t..sts  w,r,..  licuovr.  ,aa,l..  I,y  alt-Tnativ..  ,M,tlio,|s 
liir  till'  piiriMisc  of  comparison. 

Tlic  jipxTssi's  tliiis  tried  were: 

1.  CliloriiialioM  l,y  saturating'  the  roaslr.i  rhar^;,.  wit),  rlilori,,.' 
pas  uiul  U'-.irhmt:  uith  water,  as  in  the  o|,|   I'laltner  pro.vss 

2.  Direet  eyaniWe  treatment  of  the  raw  ore  after  h'ne  u'riiniin-r 
m  u  tiil.emill  with  steel  halls. 

I'lH  uKiN.viiox  Tints 
_  A  ehar-e  of  roaste,!  eone.-ntrate  was  moisteiie,!  wtih  ahout  1,V; 
ot  water,  and  plaee.l  h,osely.  withoui  any  paper  or  other  lilter  in  a 
poreelain  lunnel  uitli  Hat  (.erforate,!  .liaphrafr.n.  Chlorine  tja.s  wis 
introduce.l  from  helow  through  the  n  of  the  f,inn,.l,  and  after 
saturation,  the  eharjfe  was  allowe.l  to  ...and  eovered  for  L'4  hours 
It  was  then  lea.hed  out  with  water  and  the  resi.lue  .iried  ami 
assaye.l.  The  oxtraetion  was  found  hy  dit!Vrenee  of  head  and  tail 
assays;  it  was  also  eheek.^l  hy  preeipitatin-  the  filtrate  with  ferrous 
sulphate,  allowm-  to  settle  a.ul  eoUcetin-  the  deposited  j,old  ,.,i 
a  hltcr.    T'l^s     ,.    dried  ;;,ei   -upeiled. 

In  one  ease  the  residue  after  ehlorination  was  further  treated 
hy  agitation  with  eyani.lc.  The  results  obtalne.i  hv  ehlorination 
are  detailed  in  the  accompanying  tahle. 

The  residue  from  te.st  No.  :i  (Tahle  X)  was  further  treated  hv 
eyanide,  hy  agitation  for  4  days  with  a  solution  originally  at  U  2^{ 
KCN,  and  increased  toward  the  end  of  the  treatment  to  05%  XCN 
using  a  dilution  of  :i:l      This  treatment  yielded  the  following  re.sults' 

Gold,  Silver, 

Final  residue  after  cyanide  treatment q.OT  0*8" 

p:xtrartion  fron;  rhlorinalicin  lailinK ^i^  ,' 

Total  extraction  from  raw  concentrate...  no',  ,„', 

From  the.se  figuivs  it  w.mld  seem  that  the  results  to  he  expected 
from  ehlorination,  or  from  ehlorination  followed  hv  cvanide  a-e  in 
n..  way  superior  to  those  ohtainable  hy  water- washhrn"  nn,I  evVn;..., 
iMM.er  metlio,!  will  give  a  satisfactory  extraction  and  tli.-' ehoi.v 
would  depend  on   nOativ..  cost  undei    local  conditions. 


•  VWII.K   TUKMMKNT    OK    H^)TVIIO\    CnNcKNTu  vTK 


2:>.\ 


DlUKT    (VAMDlMi    UK    Hwv    ()he 

ll  IS  iiifivstintr  (<•  (oi.iparc  tli,'  ivsulls  ^htaincd  on  this  orv  l,y 
ilirc,-t  cyani.lidf?  wilh„ut  any  form  of  .■onr.iitiation,  wi'li  tl:o«. 
jriven  liy  tlic  conitiiiiHtion  of  riotation  and  cyanulc. 

Thf  followini,'  l.sts  w.'iv  miuif  on  portions  of  tli,.  same  lot  of 
or.'  as  was  us.mI  for  t.'st.s  detailed  in  tlio  preceding  tal.lcs.  Thr... 
rli.irir.'S  uvn-  tn.at..d;  llu-  lirst  tu.,  wre  tak.n  Inn.,  a  porti.,r.  <rnslwd 
in  a  small  fuhemill  with  manfranose-stecl  halls,  tisint;  the  following 
cpianlitirs: 

Ore.  2.')  It..;  lime,  (ILT.  Ih. ;  wat.T.  17  Ih. 

Timo  (if  (.'rindini;,  (I  hours. 

The  pulp  was  drained  on  vacuum-filter  to  2(i.4  ;   moisture. 

The  third  test  Wius  nia.l i  part  of  a  Iar^'er  pffi-tion  of  ore  erushe.) 

Ill   the  same   manner,   but   in   a   larger  mill,   for  use   with   a  L'(t()-lh 
flotation   machine. 

TABLE  XI 


DiHKl 


CV.V.Ml.lN.l  „K  K\w  ()Kf.   WirnoiT  Co.nce.ntration 


Test  No.  1. 

Wet  welKht  of  ore  taken  (gm.) 708 

Dry  weight  of  ore  taken  (Km.) 521 

Solution   added    (cr.) j  457 

Lime  added,  per  ton  of  ore  (lli.) 

Strength  of  solution  maintained  at  KCN o.l"p 

KIna!  dilution  of  pulp 31 

Tliue  under  cyanide  treatment  (days) 5 

Cyanide  consuniPM  |ier  ton  of  ore  (lb.) 4. go 


Test  No.  2.    Test  No.  3. 


708 

321 

l,4r.7 

0.2% 
3:1 
5 
6.32 


Test  No.  1. 
Gold,  Silver. 

Oz.  Oz. 

Head  assay   0.625  0.16 

Residue  assay    0.205  0.07 

Extraction  (", )    67.2  56  2 


Test  No,  2. 
Gold,         Silver, 


Oz. 

0.625 

0.16 

74.4 


100 

95 

300 

21.1 

0.2% 

3:1 

3 

4.76 

Test.  No.  ;i. 
Gold.       Silver, 


Oz. 

0.16 
0,04 

75 


Oz. 

0.895 
0,155 


Oz. 
0.13 


Cy.anide  Treatment  ok  Flotation  Tailing 

A  flotation  test  was  made  on  the  ore  used  in  Test  No.  -3  (Table  XI) 
resulting  as  follows:  ' 


WeiKht, 
Product.  % 

Head 

Concentrate   12.45 

Middling    11.45 

Tailing    76.10 


Assay-value. 


Gold, 
Oz. 
0S95 
653 
0,35 
0,055 


Silver, 

Oz, 

0.13 

1.04 


Percentage 
of  total  value. 


Gold, 


90.8 
4,5 
4.7 


Silver, 


99.6 


■''"^•    li.oTATluN     I'lioCKSS 

Tl.c  tailin,.  thu,spro.lu.M.d  was  a^nta..,l  with  ..vam,l...  with  .vsnlls 
as  sliowii  below:  Jtsiius 

■lAIil.K  XII 

CvAMi,K  Tkkaimkm  „i   Haw   Fumaiion  Ta.iix,, 
Wvt  weiH:lu  of  tailing  tal<cn,  Ion  gm. 
Moisture,  7.4',,     Dry  weight,  ItL'.O  gni. 
I-ime  added,  1  «n..  =  -!.,;  n,.  per  ton  of  tailing. 
StreUKth  of  solution  maintained  at  0.2'-^  KCN 
Dilution  of  final  jiuli),  :l:i. 
Time  under  cyanide  treatment.  :!  days. 
C'.vanide  coiisMnied  per  ton  of  tailing-.  1,  lo  n,. 

Gold, 

A.ssa.v  before  cyanidins 

Assay  after  evanidim;  "•"■"'"' 

t..-.,„.Mon   ...     "•'"" 

77.3' J 

CuMl-MdMiN    OK    .MiTIKips 

iM'f  Ihr  sake  of  ,.„n,pa,isn„,   .,■  ,nay  assume  in   viev.    „1    ..rev^n.s 
.ysnlt.  that  an  ex,n..,i„„  ,„•.,.,;   eouhlhe  obtained  fnuu  the  eoneen- 
'n.te    v,el,ie,l    b.v    tl,e   ,,l,ove    flotation    test,    by    the    tnethod    detaih.,1 
nn,nr\y.  rnast.n^.   uate,..wasl„n.    and  eyanidintr.     The  vahtes  shown 

'  ''-. '-hlhn.^  t.K.v  be  ..iintUK.ted  on  tlH.  a.s.su,Mp,ion  ,i.u  in  pn^^^^ 
"'^"    ''''';:-  ","  "  '■'""'"""■^-  '•'■""■"'■'1  ">  <!•'■  l'-.'l  of  the  n,aei,ine 

nv.n  that  finally  o.dy  two  pn.duets  wotdd  be  obtained,  eon-vntr. -e 
and  tathn,.  having  the  satne  ass.y.valnes  as  in  the  ,es,.  The  rest.li 
"t   the  flotation   t.  .1    would   tii.n  apjiear  as   follows: 

Percentaf;e 
'^^-">-^'''l"''-  of  total   value. 

T    T    ^r-'    "°"'   ''-- 

Concentrate   ...  ion-  ..  -.. 

Tai.in. ::;;:i        ;;;;;;,       '"^        y>       .oxs 

We  have.  tluTcfore.  per  ton  of  raw  ore            Gold  '      ,.           ',"  ' 

Recovered  ^ron,  concentrate:                    o..  '  Oold.        of  "^al  ^^d 

•k;,:,    V    „.12!.7    X    O.-tS     =  O.SliO  |,7.u;                <v. - 

Kecovered  from  tailinj;:  " 

0.0.5.5    >    O.S70:i    V    0.773  =  0.0-7  0.70                  4  1 

Total   recovery    n.Sfi7  $17.92  ^ 

"''•■»•''     ".,99,5  ,s.54  loo' 

Takiiii:   the    fi^rure   of   Test    .\'o.    :i    ( T;,l,I,.    \'J\    ....    ;.,.i..  ...:.    .    ., 
po*.,hie  recovery   by  dinvt   cyanide  treat.nent' we  ha ve  •     '  ^  "''    '"' 


rYAMI>K    TKKVTMKNT    OF    FI.OT ATI.IX    CONCKNTKATK  L'2:{ 


Gold, 

Oz. 

By  (iiit-i  t  (■yaiiiciiiiK   ,)  yj 

Additional  rfcovi-ry  liy  (■onil)iiuf!  inetlind..    ii.u>7 


I'crieiitage 
Gold        of  total  sold. 
$ir>.:'.o  M>.7 

-'.«:;  14.1 

Her  ton  of 

concent  rate. 


Flotation,    l.,c.    ,,er   ton   of   ore  =   '^AL^J^  ^  fi,-,-, 


Roastini;   

Kxtia  labor,  etc..  in  cyanidinR. 


13 


).no 

0..J0 


Per  ton  of  raw  ore,  3.75   X   0.1297 =     o.36 

Net  savini;  by  combined  method 2  on 

In  ad.litiot,  t„  this  the,-(.  is  a  savi,,;.  m  ryan„l,  coiismnptio,,   as 
Idllows.  per  toil  of  raw  ore: 

Cyanide 

Hy  direct  ttea.ment   eon..t,med, 

Hy  combined  treatment:  iblJ- 

Concentrate  (say.  .",  lb.  per  Ion  1   .5    y   013  __  „  ,.-  „ 

Tailin.r.  I.4     .•   o.s7 _'_■ ~       ! 


1.77 
slunving  a  .savin-  i„  cyani,!,.  nf  L'.ill)  11>.;  taki.i-  cvani,!..  at  Hie    jkt  \h 
ol  KCN  L.(,u.valent,  tliis  w,.ul.l  anioin.t  to  48e.  per  ton  of  raw  oro 
treate.].    hnn^^injr   tlie    total    savin^r   ,„   .^2.74    or   abotU    $I)CO()   on   a 
moiitlily  nntptit  of  :ir)0(l  tons. 

The  tests  friven  in  Tal.le  \o.  m  show  that  about  0,4^  of  copper 
Of  .s  lb.  p,  ,•  t„n  of  raw  coneentrat..  lin  this  ease  2  lb  per  ton  of 
raw  ore-,  can  b,.  extra..te,i  in  a  solnble  f„r,„,  an,l  nii-bt  be  re,.ov,.re,l 
as  an  additional  source  of  revenue. 


224 


rUK    ir.oT ATKiN    I'HiicKSS 


FLOTATION   ON   GOLD   ORES 

I  From   ihf-  Minttxj  and  Si  uiilifir  Pitss.  of  Xovrniljti-  L'O.   laifj) 
Tlh'   lvliti,r: 

Sir— I  was  very  niiicli  iiitt'i-fstcd  in  liir  iiitorvicw  witli  Mr.  i'.uttors 
iippoariiiK  ill  ymir  issue  of  August  21,  lit]'). 

Flotation  proinisvs  in  the  future  to  taiie  a  very  important  part 
in  the  treatment  of  sul|)hiile  gold  ores.  It  is  goinir  to  he  a  serious 
competitor  to  the  eyaiiide  i)roeess,  especially  wiiere  tiie  jire.-ious  metals 
are  locked  up  within  the  suli)hides.  At  the  present  time  there  are 
many  mills  treating  low-gradi'  gold  ores  in  California.  Alaska,  and 
Korea  that  employ  oidy  amalgamation  ami  watei-coiicenlration 
(tables  iMid  vanners  .  the  tailing  being  too  low  for  a  further  profit- 
able treatment  by  cyanidation. 

Concentration  le.^ults  will  no  doubt  in  the  future  be  improved 
by  the  application  of  flotation  to  the  treatment  of  tlie  slime.  The 
extraction  of  sulphides  from  the  .sand  can  be  done  cheaply  and 
efTiciently  on  Wilfley  or  Card  tables.  The  weakness  of  waf.  r- 
concentration  methods  duiing  the  past  has  been  with  the  treatment 
of  that  proiiuet  iia.^sinir  a  2(in.mesh  screen  commonly  called  'slinn'." 
The  best  concentrators  on  the  market  today  make  only  an  incomplete 
saving  of  the  fine  float  sulphide  mineral  which  in  many  ca.ses  accounts 
for  a  good  part  of  the  gold  cscapinsr  in  the  final  tailing.  Flotation 
is  the  remedy.     The  Suan  gold  mine  in  Korea  is  an  example. 

There  are  a  innnber  of  low-grade  sulphide  ores  (Oriental  Con- 
solidated in  Korea  and  the  Ahuska  TreadwelH  that  do  not  require 
to  be  crushed  finer  than  2.',-mesh  in  order  to  free  the  sulphides  from 
the  gangne.  Woidd  such  a  coarse  product,  where  a  I'onsiderable 
portion  of  the  stdphide  remains  on  a  40  or  fjO-mcsb  screen,  be  suit- 
able for  an  all-flotation  process?  I  am  inclined  to  favor  in  such 
cases  a  combination  i)roce.ss  consisting  of  fables  for  sand  and  flotation 
for  slime. 

Where  the  .stdphide  minerals  are  finely  dis.seminated  throughout 
an  ore  and  comparatively  fine  griiKliriL'  is  neces.sary,  I  should  think 
an  all-flotation  process  would  then  be  in  order.  However,  those  of 
us  who  have  to  do  with  the  design  of  plants  would  insist  upon 
large-scale  tests  before  deciding  on  a  flow-sheet.  Tt  is  tnoncy  wisely 
spent  where  big  sums  of  money  are  involved  in  the  final  plant. 

A.  E.  Driicker. 

T.a  Snlada.  Colondiia.  October  D. 


Till 


Kl.KCTKICM.    ■I'lll.oin     <)l      ILolWI'MlN 


THE  ELECTRICAL  THEORY  OF  FLOTATION 

By  Tjiomas  Jl.  IJ.uns,  Jh. 
(From  the  ilininrj  and  Schnti/ic  Press  o(  Novtmber  27,  iyi5) 

Intkoductiox.  If  one  turns  to  'Eleiiientary  Lessons  in  Eleetrieity 
and  Magnetism,'  liy  Silvanus  Thompson  anil  studies  the  fundamental 
prineijiles  of  frietional  eleetrieity.  as  sriveii  in  Chapter  1,  a  clearer 
idea  of  the  causes  of  'flotation'  may  he  ohtained.  After  seeing  a 
few  experiments,  sui'h  a.s  were  performed  at  the  (';use  School  of 
Applied  S'  -enee  early  in  the  year,  it  is  not  a  dinicult  matter  to 
lielicve  that  most  of  the  phenomena  are  electrical  in  nature.  For 
instance,  if  powdered  galena  ore,  with  a  limestone  gangue.  he  drojjped 
into  pure  water,  most  of  the  powder  will  immediately  sink  to  the 
hottoin.  As  the  air  enelo.sed  hy  the  particles  is  expelled  gradually, 
one  sees  the  f(U'miition  of  'armored'  huhhles,  some  of  which  may  last 
for  days.  Here  is  flotation  without  oil  or  acid.  If  nitric  acid  is 
added,  the  gas  bubbles,  formed  by  the  action  nf  the  acid  on  the 
gangue,  will  carry  wj)  paiticles  of  galena,  some  reaching  the  surface 
and  bursting,  while  others  too  heavily  h)a<led  wiili  galena  particles 
will  hover  just  below  the  surface.  These  will  form  (dusters,  resem- 
bling bunches  of  grapes,  and  when  enoi  ■  i  gas  bubbles  ,ioin  the 
clusters,  they  start  upward  toward  the  surface,  but  generally  before 
reaching  there  they  are  overloaded  by  particles  falling  from  the 
bubbles  that  are  bursting  at  tiie  surface.  The  bubbles  with  their 
loads  often  resemble  balloons,  with  the  gahna  hanging  on  to  the 
liottoms.  as  do  the  baskets  of  ai'tual  balloons.  Some  of  the  bubbles 
will  be  completely  'armored'  while  others  will  be  nearly  free  from 
galena.  Another  experiment  liiat  may  be  successfully  used  in  the 
laboratory  for  the  flotation  of  the  difficult  sulphides,  such  as  ohl 
rusty  pyrite  concentrate,  liki'  sweei)ings  from  floors  of  old  mills, 
is  as  follows:  Mix  the  ore  with  bleaching  powder,  some  carbonate 
(say.  sodium  carbonate),  and  water.  Put  the  mixture  into  a  glass 
beaker  and  add  concentrated  nitric  until  red  nitrous  fumes  are 
given  off.  Chlorine  also  will  be  evolved.  The  bubbles  of  gas  are 
so  highly  chargwl  electrically  that  pyrite  from  the  Mother  Lode 
between  10  and  '20-mesh  size  was  floated,  making  a  complete  separa- 
tion from  the  quartz  gangue.  In  this  experiment  the  nitrous  oxide 
V.  iui  ;i;"  I'u:;  * vc  ii^ciii,  ior  ii  trie  siiuic  *.  Apcriniciit  io  conduCTiru  'vViT ii 
sulphuric  acid,  no  such  separation  takes  plaeo.  Assayors  are  familiar 
with  a  similar  phenomenon  when  treating  Mister  copper  with  conccn- 


22<i 


IE    JI.OTATIDN    I'liOCKNS 


tratcl  niiru'  aci.l  id  heati.ifr.  Xitnnis  oxidts  iuv  funned  a.i.l  the 
metallic  euj)i)e)-  is  ll„ated,  a  froth  <.f  copper  being  the  result.  Carbon 
dioxKle  does  not  .s,.ei,i  to  l)e  as  a.-tisv  as  the  nitrous  oxi.h.s  or 
i-hlorine   bubbles. 

Hi,KCTKiKie.\Ti„.N  ,,1  Tin:  Hi  hbi.k.  Two  dilferent  substaiiees, 
whether  gaseous,  li(,iiid.  or  solid.  wli,.n  l)rou<ri,t  intiiiuitelv  into 
eontaet  and  moved  one  over  tiie  other,  always  produce'  elec- 
trification. Dilfereiice  of  temperature  (,r  two  .similar  .substances 
ill  fricti.inaj  contart  will  cause  el,  ■trilication,  the  warmer  usiiallv 
belli','  negatively  •■liarged.  .Something  certainly  happens  when  the 
siirfac's  of  two  ditl'..re'it  substances  arc  brought  into  intimate  emitact, 
for  the  rvsiilt  is  that  when  they  are  ,!rawn  apart,  they  are  oppositch 
cliarged.  The  nalutv  of  tile  charge  d,'i)en,ls  on  the  siibstanc.'.s.  Fur 
lul.bcd  on  -la.ss  elcctrliics  the  gla.ss  negatively:  while  if  gja.ss  is  rubbed 

"'■1 Iluioid  it  uili  bi'coine  charged  jiositivcly. 

A  blow  struck  by  one  substance  on  aiDtiier  produces  opposite 
electrical  states  on  the  two  surfaces.  Again,  the  eva|)orati.ui  of 
hquids  is  accompanied  by  ,.|cctritication.  liquid  and  vapor  i..,sumiiig 
opposite  charges,  though  this  is  only  ai)paivnt  wIi.mi  the  .surface  is 
111  agitation.  A  few  drops  of  ,.opp,.r  sulj.hate  thrown  <,n  a  hot 
platinum  plate  pnxliices  violent  electrilication.  as  the  copper  .sulphate 
evaporates.  Electrical  charges  are  set  up  l,y  various  other  means, 
.sueh  as  viliration,  disruption  of  material,  cry.stallization,  conilmstioii, 
pressure,  and  ehemical  reactions. 

It  would  seem  easi.'r  therefore  to  cleclrify  a  bublde  than  to  ke,.p 
it  from  being  electritie.l.  I  a.s,sumc  that  the  bubi,l,.s  are  .'hrlrilied. 
whelh.-r  by  means  of  air  being  forcci  through  canva.s,  i,v  beating 
air  into  water  with  bla.les,  .,r  by  other  means  Tim  next  step  is  to 
con.sid.u-  the  ])roperties  of  an  electrified  .s|>li.n..  These  may  be  illus- 
trated l)y  .suspending  two  light  sjiheres  of  <-on(luctint,'  materials  near 
each  <,thcr  by  means  of  silk  Ihread.s.  Tpon  charging  the  spheres 
vitli  like  electric  eharg.s.  they  will  rej.el  cadi  other,  but  if  a 
c(uiduct(,r  isl)n)uglil  toward  them,  both  are  attracted  to  the  conductor. 
Of  cours.'.  if  the  spheres  tmicli  the  conductor  and  the  conductor  is 
grounded,  then  the  spheres  lose  their  charges.  If  the  ,.on.luctor 
IS  insulated  from  the  ground,  then  upon  contact  with  the  s|)hen  s. 
the  condmdor  receives  a  .similar  charge  and  the  .spheres  will  be 
repelled.  Suppose  that  the  s.oheres  or  conductor  are  covered  with 
an  insulating  film.  Then  the  spheres  and  conductor  wouid  remain 
.t.s  eiu.sc  ioKciher  as  tiie  liims  wouid  permit.  Ho  air  bulibles  thrt  are 
el.'ctriti.'d  will  attract  conductors  near  them  that   are   free  to  move. 


Tin;  Ki.KcTKir.'.i.  tiikokv  of  floi mion 


Air,  lifiiit,'  ii  i)()or  conductor  of  olctricity.  tlic  l)iilililc.s  as  a  wliole 
do  not  disdiar^'c  immediately  upon  contact  with  a  coniinctor.  The 
only  part  of  tlie  surt'aie  diseharfred  is  tiiat  in  iiiiiiiediate  contact 
with  the  condnctor,  and  this  dischartrcd  tiliii  of  air  acts  as  a  dielectric 
and  non-condnctor  to  the  rest  of  the  hulihle,  whieh  remains  cliarf;ed. 
The  amount  of  eicctrificatii.n  of  the  huhhie  will  depend  on  various 
conditions,  sudi,  for  example,  as  the  amount  of  friction  jiroduccd 
liy  the  l)lades  of  a  Minerals  Separation  machine.      Increa.se  the  speed 

and  the  electrification    is  fjreater  and   the  attraction   fm nducloi's 

will  increase,  rcduciiifr  the  proportion  of  conductors  in  the  tailinir. 
Hefcrrin^'  to  1).  <;.  Campliell's  article  in  the  Mitiiiifi  uml  h')i,iini(  rim/ 
World  of  January  17.  lf»14,  the  speed  of  agitation  and  the  percentatre 
of  extraction  is  priven  as  follows: 

speed  of  lilaries, 
r.p.ni. 

1  soo    

121)0    

900 

i;oo 

The  extraction  seems  to  vary  directly  as  the  sijuare  root  ot  the 
increase  in  speed.  But  it  will  be  ohsorved  that  with  the  increased 
extraction,  the  percentage  of  sulphide  in  the  concentrate  decniLscs. 
due  to  the  attraction  of  the  small  particles  of  mixed  gantrue  and 
suli)liide.  If  the  huhhles  are  hifihly  eharjied.  the  concentrate  will 
not  he  as  clean  in  a  particular  case,  as  if  they  were  less  charged. 

\'apors  and  gases  may  he  highly  electriticd.  The  Armstrong 
hydro-electric  machine,  devised  hy  Lord  Armstrong,  gave  sparks  of 
5  to  6  feet.  The  friction  of  a  jet  of  steam  through  a  wooden  nozzle 
generates  the  charge  on  tlie  particles  of  condensed  water. 

Rkl.vtivk  ('DNnrcTiviTY.  From  the  ahov,  it  appears  that  to 
float  a  mineral,  it  nuist  he  a  conductoi-.  The  following  table  "' 
relative  conductivities  is  taken  from  Landolt  I5oriistein  'Pliysikalifch- 
Chemis<'he  Tabellen.'  ^'^\2.   fourth  edition; 


action. 

n"eii;tit  of  proili 

'■'r 

fJm. 

t;8 

:!!♦ 

.-)4 

32 

46 

2« 

.'!9 

18 

Silver    tJSl.OOO 

Copper     634.000 

Gold     455.000 

Iron    113.000 

Covellite     8,000 

Galena    3,3.")0 

Graiihite     700 

Pyrrhotite    119 

Chalcorite    91 


Pyrite    41.7 

Magnetite    1.24 

Chalropyritp    0.9X3 

ManRanes<>    di-oxide 0,16 

Cuprite    0.025 

oiderite    0.00014 

Quartz    ns;44viOii 

Diamond    0.211X10'* 


228 


■nii:  ii.irr\ri(i.\   rnorKss 


l''-'"ii  'Ins  lahi...  it  w„ul,l  scrm  that  tlir  metals  an,l  sulphi.irs 
that  may  Im-  ,vrnviv,l  l,y  tlh^  tlolatinn  ,n,-tlin,l  arc  all  .M>,„lurt.,rs 
llu.  ,.lialro|,yf.ir    li-iuv   MviMs   l,.w,   l.ut   the   H„lati(.n   i>rop(.rti,.,s  .,f 

suipln,!,.    >ninr,v|.s    vary,    a.nl    the    variali,...    i„    the   cm livitv   „f 

tlic  (htr.Tr.it  iiii.i.rals  may  havr  s.ml^tlli^^'  \o  ,1„  with  this  "tIi.. 
1"  tt.T  !!.,■  cMiductivity  „r  thr  valiial.je  mii.rral.  the  easier  is  it  floated, 
othei'  taetiifs  reinairiiii;,'  the  same. 

TiiK    iNsn.vTiN.;    Film,      The    next    imi)ortai,t    .|uestio.,    i„    the 
prohlem   IS  the  a.-tm,i  „f  the  „ils,   resins,  or  other  ajr.'Mts  now  nseti 
in  Holation.     Wnrkin-  from  the  eh-.tri,.,]  .standpoint,  it  is  neeessarv 
to  prevent  the  ehar-.-  of  the  hiiblile  fro,,,  heinsr  dis.sipated  and  thus 
l.reaking  down  the  froth,  b..fore  it  has  done  its  dniv.     Oils  an.l  other 
sui)stanees   have   a    t,.n,leney   to   eoat    tl,.     metals  and    minerals   that 
are    recovered    by    Hofation,    an.l    if    the    air    bubble    ,>    eompbtelv 
surroui„le,l  l,y  these  partieles,  an  envelope  „f  oil  or  other  dieleetri'c 
will   insulate  tl,..  bulible  an.l   prevent  th..  dis.sipation  of  the  ehan'e 
Without  a  dieleetrie  Him  abo.it  the  bubble  no  permanent  froth  voidd 
Ix'  tormed.     It  is,  therefore,  i,e  essary  to  au<l  some  material  of  r^reat 
«ii''l";tr,e  stronpth  that  has  the  ten.leney  to  e.mt  the  valuable  miiuMal. 
The  words  Mieleririi-s'  and  '  non-eonduet,.- s    .,r  '  insulators'  should 
not   be  eonfuse.i.      A    'dieleetrie'  is  a  subslanee  that   is  not   otdv   a 
"•""'oiiduetor.   but    is  also  one  that   takes  part    in   the  propa-aiion 
ot  the  ele.'trie  induetive  forees.     All  dieleetries  aiv  'insulators,'  but 
e>|uall/  jxoo.l  insulators  an'  not  neeessarily  equally  pood  dieleetries 
Air  an,i   -lass  are    far  better  insulators  than   ebonite   or   parat^n,., 
but  the  induetive  influenee  aets  more  strongly  aeross  a  slab  of  frlas,s 
than   aero.s,s  a  .slab   of  ebonite  or  parafiRne  of  equal   thiekne.ss  "and 
better   stil!    .M.ro.ss    the.se    than    aero.ss   a    la.ver   of   air   of   the    same 
thickness. 

It  may,  therefore,  be  pos.sibl-  to  use  a  frothiti?  agent,  as  is  well 
known,  that  is  n(,t  an  oil  at  all.  T  have  done  this  and  formed  froth 
that  has  lasted  for  weeks.  For  in.stance,  if  in  the  experiment 
mentioned  in  the  first  part  of  this  artich',  with  fralena  ore.  a  little 
alcohol  is  first  mi.xed  with  the  fralena.  before  the  water  and  acid  is 
added.  th<.n  a  heavy  mass  of  bubbles  and  galena  particles  will  be 
formed,  too  lu'avy  to  rise  to  thi'  surface. 

As  the  influence  .;f  the  charge  acts  inversely  as  the  thickness  of 
the  tilm,  it  is  imperative  that  some  dielectric  be  used  that  will  create 
a  very  thin  film  about  the  valuable  mineral.  The  dielecfne  mns! 
als,)  be  of  such  a  character  as  to  aid  the  formation  of  a  great 
'Piantiiy  of  small  ],ubbles  in  the  li,p,id.     It  is  dinicult  to  er:'ate  and 


Till-;    KI.KCTIUCM.   TIII-:c)KY    uF    KI.OTATKIN  •22!< 

iiiaiiitaiii  sinall  Itulil.k's  in  pure  water.     It  is  her.'  that  .surface  tension 
phenomena  prohal)ly  play  a  part  in  flotation. 

AciniTY  OK  THE  rri.r.  In  .Mr.  ('aiMi)Iicll 's  arti.-h"  lie  ^Mv.•s  thr 
folhiwiiiK  results  of  aciil  variations: 

'^*''''  K.\tra(tioii.  Wtiuhl  of  inodiKt. 

-'"•  ',;  G.n 

'•••J    t!3  67 

"■2    50  60 

"■*  r,x  35 

"•''  48  m 

"■>*   40  v« 

Oilier  tests  also  .sliow  tliat  the  e.xtraction  decreases  as  the  acidity 
111.  rcases,  but  the  amount  of  gaii{,'iie  in  the  concentrate  decreases 
much  more  rapidly.  With  an  acidiHcd  pulp,  a  cleaner  concentrate 
is  obtained.  ALso  better  results  are  obtained  if  the  acid  is  added 
before  the  oil  to  the  a«itation-tank. 

As  to  the  action  of  acids  and  alkaline  substances  in  the  pulp, 
little  seems  to  be  known,  liut  according?  to  the  electrical  theory,  the 
addition  of  the.se  .substances  causes  the  conductivity  of  the  pulp 
to  increase  preatly.  It  is  a  po.s.sibility  that  if  the  acid  is  not  added 
before  the  oil,  the  gangue,  oil,  and  conductors  are  all  electrically 
charged  by  rea.son  of  the  friction.  The  conductors  would  be  positively 
charged,  while  the  other  .sub.stances  and  the  air  bubbles  would  be 
negatively  charged.  If  the  pulp  is  a  poor  conductor,  as  it  would 
be  if  water  is  not  acitlified  or  otherwise  made  a  conductor  (pure 
water  being  a  very  poor  conductor),  the  charges  on  the  gangue 
materials  would  remain  for  some  time  and  the  conductor  (sulphides, 
e*.  would  attract  the  gangue  as  well  as  the  Imbbles  and  oil,  thus 
causing  gangue  to  be  taken  up  with  the  Inibliles.  By  the  addition  of 
acid,  the  charges  on  the  surface  of  the  solids  are  discharged  to  tlie 
grouiiil.  and  the  bubbles  and  the  oil,  which  will  not  l)e  instantly 
discharged  as  are  the  solids,  will  attract  the  conductors. 

CoNCLcsioNS.  It  might  be  stated  here  that  the  electrical  theory 
was  taught  last  year,  as  possibly  e.xplaining  flotation  phenomena, 
to  the  class  in  ore-dressing,  at  the  Ca.se  School  of  Applied  Science. 

The  above  mentioned  method  of  floating  conductors  may  be  u.sed 
for  the  rapid  determination  of  certain  ingredients  in  ores  that  are 
amenable  to  the  flotation  process.     It  requires  only  a  beaker  and  a 

^o\v    clicinicnle      nn    flnf-i  +  w^ti     Tvin/il.i,,^..^    L.^;.,™    1  „  .i         i.i , ..    ^i  ■  , 

'. "   : ■. '   ••■"=-   ==•-•:■-■      rvi-   im-   rapi,; 

approximate  determination  of  insoluble  in  a  smelting  ore.  the  method 
will   give  a  fair  result  within  a  few  minutes.     If  the  condiutor  is 


i:ut 


iiii:  I  [,(i-r\-ii,i\   riiiicK.-s 


ivadily  ari,.,l  upmi  h.v  niiri,.  .■i<'i.|.  Ihr  ivsiilis  may  ii,,t  hf  satisfju'tca-v, 
'""  ''>  a.l.lition  „f  ,,|,.i,.  ;iri,l  th.'  (lissnlviiiL'  a.'ti.ii.  of  til.-  an, I  "is 
rcilufril. 

The  •■■■n.  wirier  siiiiiiiiary  .,f  Ihr  iv,|uitvirH'rit.s  \\,r  -H.-tation.'  ,m,ii. 
Mil.  IV, 1  I'r,,!,,  til,'  i'l,','tii,-Ml  stan,lp,iiiit,  may  I,,.  ,,f  j)racli,-id  ii.s.- : 

1.  Orvs  ,'<.iitaiiiiri^'  valuahl.'  mimTals  ,,r  m.'lals  that  aiv  iron.l 
'■'.n.lu.'tnrs  iirv  thf  .miy  .m.-s  that  aiv  siiilahl,'  tor  Hotatidti. 

2.  Tn  hiKiy  th.'s,'  , -Mil, 111, 'tors,  it  is  iH'.'.'ssary  t.i  siipi)ly  ..iKiiifrli 
clo.-ti-iticl  liiihhics  fi'om  Im'Iiixv  ti.  t1,,at  parti.-lcs  i,(  th,'  coiKiiict.M's 
that  aiT  attra.-tcl:  hcii,'..  tli,.  small.T  the  buhhk..  th,'  lu'ttcr  th,.  ivsult. 
th,'  amiiniit  nf  tras  li.'iii>r  th.'  sam,'. 

:'.  Som."  (Ii.-k','tii,-  fluid  is  iic.'pssary  to  rdvcr  tin-  poiiductor  or  the 
Imlihl.'.  to  [>r,'v.'iit  th.^  dissipation  .d"  the  clci'tri,'  cjiarfrc.  The  tliinniT 
the  film  of  di.dc.'tric  ami  th,'  iri-.'ati'r  its  ,lii'l,','ti'i,-  stivii-rth,  th.^  ^'nat.T 
th.'  .'tV.vtiv.'  attra.-liv,'  \'„rrr  ami  tli.'  iimi-,'  ixTinaiuMit  will  li,'  th(> 
froth. 

4.  Som.'  mat. 'rial  iiiiist  1,.'  ad.l.'.l  to  thi'  wat.'r  t.>  iiicr.'a.sc  its 
ooiidiii'tivity,  to  ohtaiii  a  .'haii  .'oii.'.Mitratc  :  ari.ls  in  small  .piantity 
arc  now  uwd. 


NOTKS    ON     ri.iil'Al'lilN 


L>:il 


NOTES  ON  FLOTATION 


\iy  .].  M.  Cm. LOW 

iFiorn  the  Mniiii!/  ami  Si  i'  ntifl,    I'lrss  of  Dproiiiber  4,   ]9ir,  i 

•IIisTdUirAi,  SKiicii.  Th.'  sfl.'ctisr  actiiiii  (if  oil  for  lustn.iis 
iniiicrals  \v;i.s  lii-sl  disclciscd  by  llayrifs  in  istio.  In  LSH."),  Carrie 
Ev.TSon  clalioratfd  this  idra  and  also  disrlos.'.!  tlic  fa.-t  that  ai-id 
itiert-aj-cd  the  so-called  scU'ctivc  aetion.  Her  patent  ealled  for  oils, 
eitlier  animal,  vejietal.  or  mineral,  and  also  an  acid  or  salt.  The 
pr(R-cs.s  was  tried  on  a  praetieal  seale  lioth  at  Baker  City  and  Leadville 
m  l.SM!);  it  failed,  tirst.  heeaiise.  as  has  sine,,  heeti  shown,  of  the  un- 
suitability  of  the  ore  to  tlotaliou;  sei'ond.  because  her  invention  was 
too  far  in  advance  of  tln^  times.  Thou  followed  the  KImore  brr)!hers. 
first  with  their  bulk-oil  process  and  later  with  their  vacuum  sehenie. 
The  ba.sic  principles  of  oil-Hotutioii  were  undoubtedly  eov,.red  by  the 
above  inventors  and  the  work  that  has  lieen  done  since  their  time  has 
been  merely  a  buildiiifr  iij)  on  frroiind-work  laid  down  by  them.  Differ- 
ent kinds  of  oil,  ditTerent  (juantities  of  oil.  and  all  tin-  varyini:  deu'ives 
of  agitation  were  all  e.xemplitied  and  pra<'tised  by  them  in  one  pha.se 
or  another;  the  developments  that  have  since  been  made  are  but 
e|aborations  of  the  fundamentJil  principles  laid  down  by  llaynes. 
Ever.soii,  and  the  Elmore  brothers. 

In  l')02  we  saw  the  development  of  the  Potter  or  Deliirat  pro<'ess 
111  Australia.  In  this  no  oil  wa.s  used,  but  the  mineral  was  raised  by 
the  |.'eneralion  of  fras,  brouirlit  about  by  the  introduction  nf  jieid  in  the 
pulp  so  that  the  mineral  appeared  on  the  surfaee  of  the  sei.aiatory 
vessel  in  the  form  of  a  scum  or  froth  buoyed  by  minute  gas  bllbl)l,^s 
attached  to  them,  and  thus  tirst  gave  the  .sugfre.stioii  of  gaseous  flotation. 
In  1002.  also,  PVoment,  an  Italian,  was  granted  a  patent  in  which  he 
coiid)iiied  violent  agitation  with  oil  and  gas.wis  flotation,  the  gas  being 
generated  within  tiie  pulp,  in  much  the  .same  way  a.s  in  the  Potter- 
Delprat  i)roces.s.  hi  the  same  .vear,  Cattermole  came  out  with  a 
uni(|ue  .scheme.  He  first  emulsified  his  pulp  with  a  small  (|uantity  of 
oil  by  violent  a^ntation  and  afterward  .submitted  it  to  a  slow  stirring, 
action  in  a  s.'coiid  machine,  by  which  he  granulated  or  coagulated  the 
minerals  that  had  been  oiled  into  nodules,  which  he  afterward  sepa- 

♦A  paper  originally  prer.pnted  at  the  annual  meeting  of  the  I'tah  section 
of  the  American  Institute  of  Minins  Engineers,  at  Salt  Lake  City,  on  October 
4,  1915.     Read  at  the  New  York  meeting  in  February.  1916. 


232 


Tin:  I  i.in  \  ri(i\   ihock^s 


• 1  --...  -JV     Ofi-C 

L  J:^jyr^S»<-..r^T  OTrf.1  vKr  t^rf  cry  „Z.  :    ,   ~; 


Fin.   42 


rate.l  from  the  pulp  l,y  Kraviiy.     The  .ietVvt  .,f  this  process  was  tliat 
onlv  Dnrt.  nt'  tin.  ini...^....il  ,ir„,  .._„.,..i.,,^  i     ,i  .      „  . 

,■"■,.  "    , s=r-.::;!:.-.;v,:,  ;:ic  r;  St  or  it  appearing  on 

the  suriace  ot  the  pulp  as  a  seum  or  froth,  and  so  was  lost  in  the 
tailing.     This  rlefeet  of  the  Catlermole  process  suggested  the  funda- 


Notes  hn   ii.nTvrrns 


•_':<:{ 


mental  idea  of  the  pr..c<..s.s  aft.ruanl  .Inscribed  l.y  Sul.nan  I'iranl 
and  iSallot  ia  tli.ir  i.-cts,  in  wl.i.h,  iMsfiui  ,.f  KraMulatini;  part  ,„' 
tiir  .,uM..ral,  tl.,.y  Hoatcd  all  „f  ,t.  This  jKit^nt  f,.rtns  the  basis  „f  all 
the  Minerals  S,.paration  operations.  It  was  Hrst  exi.NMlfd  in  Australia 
and  m  a  short  time  rrj-haed  all  othrr  Hotation  pro,.,..s.s..s  i„  tJK.t 
i-oiintry. 

In    1!»()4.    Ma.'.piistr,,    bron-lit    onl    his   tub,.    pro,e.s.s    a    very    in 

sren.m.s  sehen.e  whi.^h  -ave  exeell,,,!   .-esuKs  on  (he  san.iv  -tion  of 

the  feed  but  was  ino,„rative  when  slime  was  present.  This  was  a 
strictly  surfaw-tension  seheme.  an,!  its  inability  to  handle  slime  was 
a  se.";)iis  liiiiitatioii. 

In  1912,  Hyde  introdured  a  tno.lilieation  of  the  Minerals  S,.pnn 
tion  proress  into  the  mill  of  the  Hutte  &  Superior  eomi.anv  at  Hutle 
Montana  This  ditl'ered  fnmi  the  reirnlar  prarti,-e  in  'that  it  in- 
troduced a  doulile  treatment,  first  ■roudnnir'  ami  then  'eleauin-'  the 
eoneentrate. 

Vsr.VMXvir  l',.nT.vTi„N-.  Karly  in  UKilt,  f  ,h,l  ..,  j,,„,t  ,],;,|  „,•  ,„„i. 
with  the  Mae,,uisten  flotation  proee.ss  and  in  the  in.stallation  of  the 
tube.plant  of  the  Mor.iin-  ndll  at  Mullati.  Malio.  This  work  was 
tollowed  by  a  lar-.-  amount  „(  e.xperiin<.ntin-  on  the  difT,.re„t  kin.ls 
ot  existing  flotation  proees,ses.  the  outeom..  of  which  was  the  develop- 
ment of  the  pneumatic  method. 

The  first  application  of  i.neumatic  flotation  f.,r  the  treatment  of  ore 
was  ma,K  by  me  at  the  mill  of  the  National  Copper  Co  at  Mullan 
I  his  plant  was  .lesiumed  and  built  by  „„.  and  was  a  smress  i„  ,.verv 
way  from  th.^  very  start.  Construction  was  started  on  Autriist  14 
^fm.  and  the  plant  went  into  successful  operation  about  April  lo' 
lf114.     The  flowsheet  is  friven  in  Kifr.  42. 

Since  that  .late,  the  metlio,!  has  been  a(h)pted  hv  nearlv  ■;';  the 
other  mills  in  the  Coenr  d'Alene  tn-atinr;  lea.l  and  lea.l-zinc  ores 
notably  the  Cold  Hunter.  Mornin?.  Hercule.s,  Hunker  Hill  &  Sullivui' 
Caledonia.  Last  Chance,  He..la.  Standard,  etc..  a  total  of  about  T.n 
cells  u,  all.  treating  from  If.on  to  2000  tons  of  slime  and  fine  sand  i,er 
day.  The  same  m-thod  also  has  since  been  adopte.l  bv  th,.  Inspiration 
Arizona,  Anacon<la.  :\ra!,'ma,  and  other  copper  companies  and  by  the 
S.Iyer  Kin-  Daly-Jmljre.  Duqnesne.  and  El  Rayo  mining  companies 
on  lead.  zinc,  and  other  ores,  making  a  total  of  some  680  cells  in  opera- 

!'"L"rJ"  *'^*'  '''"""■'^''  "'^  '■'■'^'■tion.  having  a  eombined  eaj.aeity  of  25.000 
lO  _'r>.i;uO'  Iiiji.->  pel'  ua,\ . 

The  flow-sheets  of  the  Inspiration  and  the  Arizona  Copper  plants 
are  given  in  Fig.  4.1  an.l  44.    The  Daly  Judge  flow-sheet,  in  Fig.  45.  is 


->.!» 


nil.  I  i.iiiMiMN   n(,Mi,>s 


Fjo.  43. 


iUi  iiiluresliii-  example  uf  fl„.   ncoverios  possible  on   zinc-lead    fine 
sand,  and  slinie. 

,       ""      " ' -•■••s    •!:a^:a:::,    r  r^.     jo.    HiuoiialeM     iiie    various 

Clements  composing  the  Callow  method. 

.1  is  a  mi.xer  operated  l.y  eompress<Hl  air  for  the  purpose  of  mi.xing 


Mm.>  ci.s    |.r,oi-  \rui\ 


L':!.-) 


•""1  .•-MulMlyinK  tlK.  oil,    ,|„.  a,,,  ,„„,   „„.   uat..,-,   tl...  snuu-   U,,r   ,„' 
^MTan,lu.  I,,.,n^,n,.. „„,„„„  us,.  „,,.,aM„l,.u„M<       h,  .as..,  u  In.,-,.  1 1,,- 

|-"  1    th.s  nnx..r,  or  i'a,.l„„.a  tank,  ran  l.-  ..|n,n„at..,|,  .s,.  that  tl,..  .,,1  ,s 
I'.l  'Invrt  nit,.  tl„.  ,Mili  aii.l  tli..,!,,-  into  tli.  s..,,arato,-%-  ,.,.11 

It  l.a.s  l„.,.n  ,.r,.v,..l  .....■.■li,,siv,.|y  t|,a,  aritati,,,,  p/r  .„    is  „„!  ,„■,•..^ 

";''•     •"  ••^"'•'•-'■"l  tl„tati,M,   l.ytl,,.  p„,.un,alH.,„,.llH„l,      I,,,,, f,!,.. 

pa,.,:,  a  I'a,.|n.,.a  mun,.,-  f,,,-  ,.a,.l,    f,,,,,-  n„.»:l,iM«-,-,.lls   was  install,,! 
Ins  n.,..n,.,l  .1,,.  ,|,i,.k..n..,l   ,V..,1   fmn.  a  l)„n-  tank,  win,.),   ,V,.,|   was 

•■  .■vat-.l  l,v  a  (,..lt.an.l-l,u,.k,.t  d-vator.     Tl,..  ..i|  was  r...|  int„  tl,..  1 , 

"'    ";■  "l':7'""-  "'"I   ""•   -Hxintr  tl,..,...  s..,.v..,l   all    |„.,-,,.,s,.s,  s,n,...    ,|,.. 

n-l,sw,,,,,,,.   ,1,     ,.,H,,,,.asw,.,...  ,on.,,M,.,,.,j,,s,  ^     ,  as  with 

tli'-m.      I|,,.n.,,„,,„,,„s,..,f,l„.„,  ,„„,is,,|,„„,,,sl n  al,an.i.„„..l 

i    is   th,.   „„t,al   .„•   ,„„^rl,in^.   s,.,.a,-,it..ry    .-..H.      j,    ,.„„sists   .,f   a 

ank    '•"-.'Mt^.l„„,„v..,.allan,i24in.ui,l...withal„.tt,„ni„,.li„..,| 

.   on,   ._,..   4   ,„,.l„.s  „r     all    p,.,.   ,„,„  ;    „    ,s,Oin.    at    ,1,..   shallow 

'"V  ;"•  ''""'"'"   •!"■  'l-l.-.st  ..„.!.      It    n,ay  I,..  1„.,|,   ,„■,.;„„,,. 

St. ..-I  or  w..,.,|.  pr..f..,-al,ly  w,,o,l. 

Fifr.  47  an.l  4S  sl,.,w  tl„   ..,.11  i,,  .iHail.     Tl„.  hott..,,.  ..f  ,|,„  ,ank  .-on. 
.si.st.s  01  a  pun.us  n.,..li,„„  n,a,le  „r  f„ur  thi..kn.>s.s.>s  of  l„„s..lv  ;w,v..„ 

io'ni'Vr;  i  ';■■''"■'■'''.  ""'""■""' '  •■ "  '""'^'"^  "•'  '"•'••■'"-"■''  -'"■ 

"  I— nt  l,ul.„,s  wl...„   ,.n,l..r  air-pn-ssn,-...     Tl„...„,,l.   ,|,is  p„,.„.s 
''"""   '■"•"•'•••'--^■•l    "u-   is    f..,-,....l    ,,.v    „„.    ,,,,„,„,   ,.       p,,^,,,,^    ,,^.,^ 

';'•  '"'.V  otl,..r  ,...,.a,„i..  ,nat.M.iaI  n,ay  I,..  „s..,l   t.,  ..nsn,v  tl„.  n,.....ssarv 

.n.  ^  ,,,v,.o„  .,,   „,e  ai,-.     Son..-  .,f  ,l„.so  „av..  1.......  tri,..i.  Unt   .o,- 

.ra.t,cal  an.l  ,„....l,an„.al  r,.i.sons  tl,e  lo.,.s,.ly  w.,v..,.  ..anvas-twill  s....n,s 

to  serve  all  purposes  hotter  tl.a,.  anytl.i,,^  els,.,  an-l  has  he..,.  a.l..pte.i 

as  th.'  stan.iai-il   pomii.s-hi.tton.  eonst,-i„.tioi. 

The  spa..e  ,„..Ien,..ath  this  p.,-.„.s  n,..]i.,.,n  or  i,otto,n  is  snh.livi.i..,! 

a  -e'w  thT'"'"''''"''-^'  '.■-'■;—<>  '".v  an  in.livi.iua.  pipe  a... 
%ahe  «,th  the  „,a„.  a.,--p,pe  F.  Hy  ,his  n,..ans  the  air-pressure  to 
oaeh  eo,npart,nent  .-a.,  he  r,.gulate,l  .  l.y  throttling  the  valv.O  to 
-m-spo,„  w,th  the  varyin,  hy.lraulie  hea.i  withi,.  the  Lk  L 
as  to  dLScharpe  a  un.fonn  a,no,.,.t  of  air  tl,n,ugh.„,t  the  len^rfh  of 
tlu>  Lotto,,,  an.l  n.a.ntain  a  uniform  aeration  of  the  eontents  A 
pressure  ot  fn>,n  4  to  5  Ih.  is  generally  use,!  and  eaeh  square  foot 
of  porous  med.um  re.,uir.>s  fro.n  8  to  10  eubic  feet  of  free  air  per 
minute.  1'^' 

„  ^'■■'■•":cii  riiK!-  ;;;    mr  tank   is  |)rovid.'d  with   a  lin  and 

a.,  overflow  fitter  for  the  reeeption  of  the  froth  to  be  disehar^d 
The    lower  end   of   the   tank    is   furnished    with    a    spi^ot-disehar^e 


236 


TH£    FLOTATION    I'HOCKSS 


■f*^  »„e  ^mmi  r 


Flu.   44. 


Mtt.Mi  with  a  plufT-vnlv...  ,.,„.rate.l  by  .,  float,  for  tl,  purpose  of 
'■ui.ntammf.  a  u.nforni  wat.r  ],.v,.l  within  fh.  tank,  thus  in  t.ir., 
s.r..r.ng  a  u.nlonn  a.ui   constant  .iisd.arp.  of  iVoth  und...-  all   th- 

Iho  wator-lovel  may,  ot  cours...  h.  varied :  In.t  it  is  n.snally  maintain,.! 


NUTKS   ox    Kr.OTATlox 


2r, 


"t  ■'t-ut  10  to  12  i„cla.s  lH.|ow  the  lovd  of  ,),..  overflow-lips      The 
a.  m,  ,s  .  ..ha....,  thro,.,,,  U.  spigot  and  the  frothy  c-on^^.trate 
o.n   v,.d  hy  ,aea„s  ot  th.  .s,.l..-j,„ttors  to  the  pump  D4.  theuee  to 
the  deaner-separatory  .ells  n.arked  C.     This  cleaner^ell  is  .  ...aehin 
ot  the  san.e  eonstru,.t,o„  a.s  the  rougher:  in  operation,  however    it 

;: i;:;:^, k' ;'>; ^ ^-'-/--i^— ^ ♦'-'  taiii„g  fro,;. t,. ^ ;.; 

s  pumped  l.y  />-2  ha,.k  to  the  original  f,.ed.  and  thus  a  elose.l  eirenit 

na.n.a..,ed  on  th.s  portion  of  the  feed.     The  eoneentrate  fro.n 
e  eaner  .s  tue  sh.pp.ng  or  finished  product.     Dump  l>.,  can  well     e 
.' hm„,ated  hy  sHtmg  the  eleaner  at  a  h.uer  elevation  and  eonl     i^ 
|lH-o.|.he.-froth  to  .t  hy  gravity.      Tsually  one  eleaner  serves  n>ur 

f'AKA.  ..K,.  OR  S..:h.ks.     The  maehine  n.ay  he  ru,.  either  u,  parallel 

1  .eli...     Recent  e.xper.ence  goes  to  show  that.  o..  so„,e  o.-es  at  least 

e  se.-.es  treatmct  gives  a  slightly  better  tailing;  on  others  it  does 

ot.     I     ,s  unne,.essnry  to  extend  this  ar,.ange,nent  of  cells  beyond 

.cells  ...  ser.es      In  a  heavily  n.inerali.ed  ore  this  arrange,."' 

i'      t    7;    T"":  ""'  ■"  ""'^  "  ''''  *""  ■•""^•'--onc;:ntrate 
m.ght  be  of  lugh   enough   grade  to  omit  the   re-cleaning  operation 

the  onV     TN   "  T"'  ""'  ^"  *'"  ^""^■•^  '"'^"'t  '-  r.;u.-ned    ,  to 
he  ong,nal  feed  .n  the  same  way  that  the  tailing  is  returned  from 

number  of  such  combu.at.ons  is  possible.     At   the   In.spiration    the 
ongtnal  fee,    goes  to  12  prin.ary  roughers.  the  tailings'from  wh    h 
a      class.hed  ...to  sand  and  slime,  the  sand  going  to  tables  and 
sl.n.e   be.ng  returned   to   12  secondary  roughe.-s.     The   concentrate 
fron.  both  the  pr.n.ary  a..d  .seco..darv  roughers  go  to  fou  t^;^ 

and  the  cleaner-ta.ling  hack  into  circuit 

F,.oT,t  Fo.^MAT,ox.  The  froth  is  generated  as  ti,e  result  of 
>n.iect,ng  the  tl,.ely  divided  air  into  the  bottom  of  the  re,dv 
:-.,ls.hed   nup;   .t  eonti....es   to   form   and   to   ove,-flow   so   lo...   as 

..nnshed  w.th  p,.lp  of  the  r-roper  consistence,  prope,.lv       .. 
:>ll'  »  .0  nght  ,,uan„ty  and  kin-i  of  oil  or  frothing  a.^en,      Measured 

:;;;  T't:  i7  r'  ^•"•;"  r  *'•"'• ""'  *■'•"'"  '""""'-^  -"-  ^^ 

Horn    14  to   ](,  niehes  m   depth  or  tbickm^    .,,   i  r  , 

1  ,         „  '  jiii   i>i    11,11  Kuiss.   aiicl   accordmt'  to   the 

<  .aracer  of   ore,  k.nd  and  quantity  of  oil  ,.,rod,.ced,  will    ,e    „ 
T  lc.s  volum.nous.  .-oarse  or  fine  grained,  d.-y  or  waterv-all  of 
-"-I't.ons  be.ng  ad.justed  by  the  regulation  of  the  Ui,',,  „..  J.l^Z 
•"  '"1  an. I  ine  quanfify  of  air  injected  '         ■' 

In  the  case  of  so„,e  ores,  rien'.n  sulphides,  when  a  con.pa.-atively 


238 


TIIK    KI.OTATIu.V    I'UOCKS 


— D»Lr- Judge  Mili  

TcsT  N'  34. 


Fir,    4n. 


lou-.grade  .on...,,. rat.  w,ll  sutli,.,,  ,h,  ■,,,,,„,,■  ,„^,,  „„j  ,,^,  „„„,.^^^,,.^. 
'■•"    on    l.nv-.ra,i,.   ores   havin,.   a   l,igh    ratio   of   eon,.,.„trat.o„ '  a.ul 

,,  ^:n..-.:;;:t::;:  j,;;,-;!;.-,  a  OiraiiiT  is  d('S!rat)li> 

I  ii.p-DENSiTy.    TlK.  pulp  to  be  treated  may  be  of  varjing  density' 


XUTKS   OX    FLOTATION 


239 


from  2J:1  water  and  ore    un  tn  'i  n»-  <;    i     <• 

and   sU,„e   the   Conner   r.:!^ i^^ ^^Ir^,^;    ll  ]:T;J  :;:::l 

ihe  pa.ticular  density  ,s  not  a  matter  of  so  ,„,.,.!,  HMportan,..    .s 

t  ,t,    .     ,u.  pulp  re,.Mres  a  re-adju.tme„t  of  the  oil-supplv. 

'  "    'I  UMtUy  ot  0,1  inereasmg  i„  proportion  to  the  inereas,>d  vo   nn. 
'"    f'"'P    I'Hl.'l-'.denl  of  its  solid  eontent 

50  t^^^s'"'"?.  ;  ^   "'"'"■''   '""•■>^^*^'   J''^"-   ^'^^"^^--d    ro„.hin,.,.ell    is 

"II.    s.iiHi  ,iM<l  sliiiie  onlv  are  treated  at  the  .-■.»..     .    -o  ♦ 
1'io.vss,  and  Its  ,s()()  f„ns  per  s<>etion  is  t, t  ,1  i.    •.  t  ' 

only  the  sinne    from   the  prin.arv   tailin-  after   the  s...  1    . 

removed.     This  srives  an  aver.-e  of  W'    ♦"  "'   '"''" 

A-  „  '  ■'^'^'^*'"'   "t  •^■>'>  tons  per  roil.' I  n"-eell      Th,. 

-  «:*  rou^hers  run  in  parallel,  and  18  el  ane J      ;\"  .,';:"f ' 
approximately   57   tons   per  rou.hinreell,    or  4"'  t  ns   pj       rf 
I'oiisrhiiisj  and  eleaninp.                                                             '^  "    ''"' 

Some    tests    have    shown    little    differenee    in    r,.eoverv  «1,  m 

n.nn>ns  45  tons  to  the  eell  or  65-  hut  the  r.        "."""'■'■  "'"""'• 

on  --lea.  ore    .5  tons  per  eell  is  an  average  ol^.lr  ' ' 

'"•"•tors.       Ill,,  puie-oils  are  frood  frothers-  m.,!  t-.,.  .      1  •. 
Mihdivisions  ,,re   ^.ood   eolleelors       O,     I  '  ""  '""'"""- 

<-....l-l,>r.  40C,  „„„,,„  „„„„„.  ,„„  „^^^,  ^^^_,  ^^,,,  ^,  ^^^  ,1  .i» 


1>4(I 


IIIK    Fl.nTATluN    I'liOCK? 


the  Daly-Jiidiic  we  usrd  4(t';  cnnlc  coal-tar.  40',;  creosote.  20'; 
I)iiieoil.  Ill  the  Coeur  iTAleiie  on  zinc  ore  we  used  straijrht  wood- 
creosote:   on   the    Xalidiial    I'opper  ore   |)lain    tiiri)eiitiiic    will   work. 


liwt    pine-oil    is   helter 
Tiftntiftv-  III'  Mill  T>iivfiif. 


At    tile    Inspiration    we   used    from    U    to   2 


.*     ♦l.„     lA,.!..     T..    1,-. 


and  at  the  National  0.:i  Ih.  ■  ;i  is  suiHcient.     In  the  experimental  work 
at  another  plant  the  coiisuiiiption  of  oil  was  approximately  one  pound 


NOTES   ON    FLOTATION 


241 


of  mixture  pur  ton,  but  sincp  the  outire  plant  has  l)et'ii  in  operation 
and  the  eirciiit-water  is  reclaimed  and  used  ov.t  iigaiii,  tlie  oil 
eonsumption  ha-s  dropped  from  1  to  O.-'k')  lb.  The  proper  kind  or 
kinds  of  oil  and  the  quantity  requisite  eaii  oidy  be  determined  at 
present  by  tentative  experiment;  so  far  no  scientilie  short-eut  is 
known. 

CiiAiucTER  OK  FiiOTir.  The  nature  of  the  froth  made  by  the 
pneumatie  method  has  the  distinctive  characteristi"  of  being  iinstabh- 
or  ephemeral,  that  is,  it  quickly  dies  when  removed  from  the  action 
of  the  injected  air.  The  bubbles  composinf<  the  froth,  beinfr  generated 
under  a  hydraulic  pns.Mire  varyinj;  from  M  to  40  iiiciics,  on  rising 
above  the  water  and  to  the  froth  level,  burst  by  reason  of  the  lower 
surrounding  atmospheric  pressure.  On  bursting,  they  release  the 
mineral  attached  to  them,  but  this  in  turn  is  caught  up  by  those 
bubbles  immediately  following  behind.  The  instability  or  stability 
of  the  bubbles  will  depend,  to  some  extert.  upon  the  oil  used  anil 
the  nature  of  the  gangiie.  I'ine-oil  makes  a  very  brittle  froth,  which 
liies  immediately  on  arriving  at.  the  surface.  Creosote  and  light  oil 
make  a  more  elastic  envelope,  which  at  times  wi!i  expand  into  bubbles 
3  to  4  inches  in  diameter  before  bursting.  The  pine-oil  l)ubbles 
will  rarely  be  over  i  or  i  inch  diameter.  Ca.stor-oil,  olive-oil.  candle- 
makers'  oil  (oleic  acid),  palm-oil.  sperm-oil.  and  other  oils  of  n 
lubricating  nature,  have  in  general  been  replaced  by  oils  more 
or  less  soluble  or  miscible  in  .■■ntpr— such  .-ls  turpentine,  pine-oil,  and 
all  the  coal  and  wood-tar  distillations.  The  v,ry  volatile  oils,  siidi 
as  naphtha,  gasoline,  ether,  alcohol,  seem  to  serve  very  little  purpose 
except  as  a  means  for  making  the  pitchy  ingredients  of  tiie  tars  more 
soluble  or  miscible. 

A  large,  coarse,  and  elastic  bubble  seems  necessary  to  tlie  recovery 
of  coarse-grained  mineral,  but  for  the  very  fine  or  colloidal  mineral, 
a  small  and  comparatively  brittle-  bubble  is  necciwary. 

PowEK.  The  National  ropi)er  Co..  using  approximately  O.W 
cubic  feet  of  air  at  4  lb.  pres.sure,  and  treating  500  tons  per  day  on 
«  roughers  and  2  cleaners,  required  :ir)-hp. :  this  equals  ^.')  hp.  per 
cell,  or  12.53  tons  per  hoi-se-power,  or  1.25  ku. -hours  per  ton. 

Another  conspany  u.sing  ai>pniNimately  <1600  cubic  feet  of  air 
at  5-lb.  pressure  and  treating  2400  tons  per  day  on  48  roughers 
and  12  cleaners,  required  210  hp. ;  this  equals  3.5  hp.  per  cell,  or 
11.  t5  tons  per  horse  power,  or  1  50  k^v.-h.ours  ner  ton 

The  Inspiration  experimental  plant,  using  api>roximat.'ly  O.^O 
cu.   ft.  of  air  at  5-lb.  pres.sure  and  treating  200  tons  i)er  dav  with 


242 


THE    KI,()T.\TI().V    I'KUCESS 


1  ^Tv"-j'^-!^v^>-»4>'^^.^^4^=4^-^..i^o:r^rj^ 


M 


./»- 


o 


NOTKS   ()\    KLOTAIIoN 


24:{ 


4  roughers  and  1  half-size  cleaner  required  25  lip.;  deducting,'  4  hp. 
for  two  2-in.  centrifugal  pumps,  this  equals  20  hp.,  or  4  hp.  per  cell, 
or  10  tons  per  horse-power,  or  1.79  kw.-hours  per  ton. 


A  maximum  figure  would  be  2,J  kw.-hours  per  ton  of  feed,  using 
5  to  5J-lb.  air-pressure,  generated  by  a  Roots  or  Connersville  positive 
blower. 


***  Tin:    H.dTATKiN     ncK  KSS 

Cost.     Tin.  .,il-,„i.M„n.s  K-'norally  in  us,,  will  ,.„M  In...,  1.25,.    ,„> 
to  .Je.  p.T  II..  .Irpendinj?  o,.  tho  j.n.,,„rtio..  of  ,.,v.s.,l  an.l  other  hiH,- 

priced   oils    .iscd,    hut    ]  .U'     nor    Ih     uill    Iw.    ..    ..„.■ 
'.,         ,  •   . '"   '^'~-  P*^  '"•   ^^'"    >'<'  a  sate  averagro  on   most 

oils.  A  co„su..ipt.„„  of  1  to  \\  Ih.  per  to.,  or  from  1.25e  to  4  5,- 
per  ton  of  foe.l,  s..y  21....  woul.l  he  a  safe  avej-age.  The  lahor." 
of  course,  ^y,ll  va.-y  with  the  size  of  the  phu.t.  At  one  plant 
cons.st.nK  ot  (JO  ..ell.s.  tuo  ...en  per  shift  operate  tl  entire  plant 
oqu.valent  to  a  eost  of  1},..  per  ton.  (),.e  ma.,  per  shift  on  a  2.1()-ton' 
plant  will  mean  a  eost  of  5,4e.  per  ton  in  n.aintc.anee.  Assuming 
a  I.le  ot  three  ..lonths  per  hla.,ket  and  50  tons  per  eell  a..d  an 
allowane..  f.,r  repairs  to  hlowers,  moto.-s.  p.imp  etc..  we  have  \e 
per  ton  as  a  liberal  esti.nate. 

Power  at  le.  per  kw.hour   ($60  per  hp.-vear.    a.,d  2.^   kw -h<...,-s 
per  ton  equals  2.;x..  per  ton  of  feed. 

Summarized,  my  esti.nate  on  a  20()0-ton  pl.,.,t  will  stand  app.-oxi- 
iiiately  as  follows,  in  ee..ts  per  ton  of  feed : 
Labor    

Oil    '■■'■'■'.'.'.'.'.'.'.'.'.'.'.'.'.'. ^-^^ 

Maintenanre    ^-^^ 

Power    •^•5" 

2.50 

Total    

c.vn 

Or,  n  plant  of  250  tons  the  .-xti^a  lahor  wouhl  bring  it  up  to 
approximately  lUc.  per  to...  Actual  figures  f.-o..,  a  large  plant  of 
over  2000  tons  enve  fi.le.  per  ton.  The  flotation  feed  i.i  this  ease 
represents  G0%  of  the  erude-o.-e  ton.iage  or  :].5e.  per  ton  of  erude 
ore  treated. 

T.n:.,H,KS.  So  far  no  satisfai-toi-y  explanation  of  flotation  phe 
nomena  has  been  advanced.  At  my  instigation  and  u.ider  my  direetio,, 
a  larg.  amount  of  research  work  luus  been  do..e  i.,  an  earnest  c.deavo," 
to  formulate  so.ne  logical  explanalio.i.  a..,l  perhaps  to  find  s<.me 
scientific  way  of  eondueti.,;.  ..xperime.its  in  lieu  of  the  empirical 
methods  now  in  vogue.  While  this  purpose  has  not  vet  been  fullv 
attained,  the  experiments  have  resulte.l  in  the  formulation  of  a 
theory  that  appears  to  be  well  grounded  and  that  mav  pn,ve  of 
value  to  others  engaged  in  this  bra.ich  of  mrtallu.-gv. 

Much   work  has  been  ,lo.,e  at   the  Mellen   I.i.stitute   at    I'iit.sbu... 
iH.dcr  the  direction  of  Raymo.,,1   ('.  lijuon.  a.id  lately  bv  .Tames  A~ 

Block  at  the   loenl   KfntJnii   ,,e  <1,„   tt     o     i> i.  ^..     '_      '_. 

ot  some  of  th.s  work  are  summarized  i..  the  following  stateme..ts: 


m. 


NOTKS    ()\    KI.OTATIiPN- 


lm; 


In  .o„si.l..n„^,  flu.  ,.on,HM.tio„  lu-tu.-M  riotatio,,  i,l,..„o„H.na  an.l 
tiio  i.l.ysi.-al  properti,.s  ..f  tl...  n.in.Tals  n.M.vnuMi.  tlMTc  arc  two 
parallelisms  to  he  noticed: 

First:    [t  has  he..,,  „otiee,l  for  some  ti,ne  that  the  „.i„e,-als  whieh 
Hoate.l    we,-e    not  easily    wetted    hy   water,    while    those    whieh    we.^e 
•■asily  wetted  did  not  tend  to  eo,„o  up  with  the  froth.     This  is  the 
ms!s  ot  ahont  the  only  th-ory  that  has   heen  widely  eireulated  up 
to  tl„s  t,n,e.     It  is  well  state.!  I,y  Iloovvr  in  his  hook,  '(oneentratinp 
Ores  hy  Motat.o,,,'  the  first  authoritativ..  puhli.>afion  on  the  suhject 
S.von.l:     lhe,-e    ,s    a    parallelis,,,    hetween    certain    .d.^efro-stati.- 
-■hai'aetensties  and  tne  tlotati.M,  properties  of  ores,  as  will  he  explain...! 
In    the    theory   first    menti..,,...].    it    n,ay    he    .le,„.,nstrat,.,l    hy   a 
r.ons,.  ..ration    of   surface   tensions   and    contact   angh,   that   certain 
floatahle  minerals,  such  as  galena,  will  float  on  the  surfa.'c  of  still 
uat.T  wlnle  ganjrue  pa,-ti..l,.s.  .n,  th..  other  han.l.  p.,s.se.ss  a  jrreater 
.■Hlh..s,ye  attraction  for  the  water  than  the  wat.-r's  cohesiye  attraction 
tor  Itself,   and   are  therefore   drawn   thr..!,-!,   the  s,irface  fil,„   into 
th..  int,.rior.  where  they  sink  hecaus..  of  th.'ir  fjreatcr  spe.-ifi,.  grayity 
rhe.se   properties  of   floatahle    minerals   an.l    ganjjues   are   increa.s^d 
by  the  p,-,.s..n,.e  of  oil  and  aci.l.     Oil  sti..ks  to  fjalena  with  greater 
t.'i.acly  than  it  sticks  to  silica,  and  an  oil  surface  is  far  less  ..asiiy 
wett...l  than  a  galena  surface.     The  aci.l  in  the  water  causes  a  still 
irreater  diflfei-ence  in   the  yarious  .surfa.'c   tensions.     This    it  s..ems 
IS  without  question  the  explanation  of  such  flotation  a.s  is  ohtained 
hy  the  Ma.'nuisten  process,  in   which  th..  ..,.e  particles  are  lift.'d  to 
the  surface  and  those  remainin-  are  removed  hy  skimming  the  surface 
layer  of  the  lir|iiid. 

As  r..gar<ls  the  se.-ond  parallelism  mentioned,  it  has  heen  noticed 
tliat   ext,-c,„ely  small   am..unts  of  certain   colloi.hd   impurities    such 
as  saponine  or  tannin.>,  were  detrimental  to  flotation,  while  others 
sn.'h  as  Congo  re.l  and  methyline  hlue.  ,lid  not  interfere    and  were' 
If    anything,    heneficial.     In    classifying    these,    the    i„j„ri.,us    ones 
generally  ..ame  un.l..r  the  head  of  what  physi.'al  chemists  ..all  ..lectro- 
negatuv   ,>ollo,ds.    while   electro-positiye   .-olloids   were   not    harmful 
ihis  classification  is  derived  from  the  fact  that  suspen,l..d  particles 
will    generally    migrate    when    placed   in    an    electric    fi.l.l.    and    the 
class,fi,.at,on  comes  naturally  from  the  c.irection  of  their  migration 
n„s  migj-ation  is  called  el..ctro-,,hore.sis.  or  electrical  endosmose,  and 
■■^'  -r.w  rcmiit  or  ii,e  fact  (hat  the  iiqui.i  containing  the  pariicles  forms 
eontact-lay.rs    around    them,    similar    to    the    surface-films    formed 
wiien   liquids  come  in  contact  with  air.     These  contact-films  almost 


246 


TlIK    FI,()TATI(l.\     l'Hil(f> 


mvanahly   have   a  .l„r,.r,.M,..  of   pofntial    l,Hw...n   their   in,,..,-  an,l 
outer  mirlaces.     Thr  (il,,.  „f  an  air-water  ......taet  ha«,  for  i.mta,,,... 

a  ci.fr..r..,H.e  ot  Omr,  volts,-  an.l  oil,,.-  .■oMta..t-fil,n.s  lu.ve  sunilar 
charges  nus  eauses  the  partieles  to  aet  like  eharfjed  soli.ls.  and 
to  be  attrueted  by  eiectri.    eharjjes  of  opposite  sip,, 

The  eharsres  o„  solids  a„d  „o„-,„i.s..ih,e  li,,,nds  ean  I ,„v,.,„e,„lv 

studied  on  the  statre  of  a  l,lie,-oseope. 

This  work  led  naturally  to  the  sturly  of  th,.  eha,.;es  .xhibited 
l^v  various  ores  and  ,ni„erals,  an.l  in  ,i„„  work  an  interesting, 
paralh.hsn,  was  ol,,s<.rve,l ;  nan.ely.  that  floatable  ,nine,-Ml.s  see,,,,.!  to 
have  positive  eha,-es  and  non-floatable  t;antr„es  nesrativ-  eharL'es  = 
So,,,,.  jranp,„.s  were  found  with  positive  ehar^es,  but  thev  we.^e 
Huira.denstieally  ha,-d  to  handle,  havinir  a  tenden.v  to  e,;,„e  „„ 
with  the  troth.  These  eharges  son.eti.nes  uny  with  the  aeiditv  or 
akahnity  ol  the  li,„„d.  and  this  variation  is  not  ineonsistent  with 
the  etreets  of  acidity  or  .dkniinity  on   t|„.  flotation  of  ores 

It  has  been  noti,.ed  that  these  ele.-tn.-statie  properties  .!epe,„l  on 
the  enndit.on  of  the  surfaee  of  the  pa.li.-les  an.l  not  upon  the 
co,npos,t,on  of  the  „ias.s.  Kor  instanee.  lea.l  oxide,  whieh  is  onlinarilv 
negative  or  neutral,  when  eovere,!  with  a  sulphide  eoati,,,,  takes  upon 
Itself  a  po.sitive  eharge. 

AltlM.,.ph  the.se  eharges  are  sniall.  ,vent  work  on  the  eoaKuh.l.on 
and    defloeeulation    of  sli„,e.    on    the   .•oaKulation    and    dispersion    of 
colloids.  an,l  along  .similar  line.s.  shows  that  the  eontaet-tihn  eharges 
have  an  nnportant  bearing  on  the  dispe,.si,u,  or  eohcrenre  of  particles 
suspended  in  li<,ui<l  ,ne,1iu„,s.     r„   ,i„e  su.spensions  and  in  colloidal 
solutions,  these  charges  may  often  be  ncitralixed  by  the  int,-oduetio„ 
of  oppositely-chargcl  ions,  and  pre..ii)itatio„  will  gencrallv  take  plae,. 
whenever    these    charges    fall    below    certain    limits.     Oppo.sitivlv- 
charge.l  contact-films  generally  have  a  tendency  to  absorb  each  otheV 
and  to  coalesce,  while  .similarly-charged   (il„,s,   if  their  char-es  are' 
great  enough  to  ..vercome  natural  eohesivene.ss.  do  not  see,,,  to  coalesce 
hut  to  rep.l  each  other,  and  if  the  weight  of  the  particles  is  .small 
enough  m  relation  to  their  si/e  and  surface,  permanent  dispersion 
will  lake  place,  the  particle.,  distributing  themselves  through  a  liouid 
in  much  the  same  manner  that  a  ga.s  will  fill  a  container. 

In  view  of  the  above  ob.servations.  it  seems  possible  that  t^otation 
IS  due  to  differences  in  polarity  in  the  charges  on  the  various  particles 


— -/-■• .tu,  .,i,i!,u<tiir.  i;>i4.  27:  ZVi  and  2S:  367 

'Kolloid    Chcmische    Reihrftc.    2S4 
89:  91,  1914. 


y.rit.     fiir    Physikfilische    ChemW. 


NOTKS    ON     FI.OTATllIX 


24-; 


.;    ..r...  ,u,.l  o„  Ih,.  I,ul,l,l,.s.     Sin.v  oil  ,.o.„a-l  til,„.s  and  a,r  .nnta.t- 
('  ".s  have  iH.th  Im.,.„  pn,v...|  to  luiv..  ....jfativ..  ,.|,arj,^..s,  th.    positiv-lv 

'■harfr,..!  minerals  mi-ht  a.lh..r,.  to  ..ill,,,-.  Th,.  hMl,M...n,anth.s  n.'a 
H-.talion  ma.'liin,.  arr  un.louht..||y  co.nposci  ot"  oil.  ,„.  of  oil  in 
emulsion,  since  pure  water  alone  uill  not  fn.tli.  The  sjime  forees 
tlieri,  that  eau.s,-  oppositivHy -har^^.,!  eolloi,is  l„  awlomrrate  an.l 
preeipitaf..  eaus.-  the  minerals  to  a.lhere  to  the  oil-eover..,l  bubbles 
a"<l  the  ..une  fonvs  that  keep  tl,e  p,n.,i,.l..s  of  an  oil  emulsion" 
•lispersed,  kiHjp  the  (?ant,'ue-partieles  rep,.lle,l  fro,,,  the  bubbles 

Kxpresse,!  brietly,  the  theory  is  a.s  follows:    That  oil  Hotatioi,  is 
an  eleetro-statie   j-ronss.      It  is  a  s,.i,.ntitie    iaet    that   when    a  solid 
partiee    is   suspen.h,!    in    wate,-,    the    water   will    form    around    th- 
partiele   a  eontact-filn,   that  generally   possesses   an    eleetri..   eharue 
th.^  amount  and  polarity  of  whieh   will  depend  upon  the  nature  of 
the    surfaee    of    th.-    partiele    and    the    .leetrolvte    in    wl,i<-h    it    is 
suspen.led.     The  presence  of  the.se  ehai-f^es  ean'be  de.nonstratnl  bv 
the  fae    that  the  particles  possessing  them  will  ,„if,M-ate  when  placd 
•"  an  e  ectrie  field.     It  ha.s  been  demonst,-ate,]  that  floatable  parti.-Ies 
have    eharpes    of    one    polarity    (positive),    and    that    non-Hoatable 
particles  have  ehar<?es  of  the  opposite  polarity   („efrativ\  and  that 
the  froth. s  eharcfcl  ne^^atively  and  so  att,-acts  the  positivelv-eharRed 
or    flontable    minerals,    an.l    repels    the    negatively-charRe.i'  or    n.,n- 
floatable   ones.     It   is  this,   it  is  believ.-.l.    that   cause.s   the   floatabl.. 
•"inerals,  such  as  galena  or  sphah-rit.-.  to  a.lhere  to  the   froth   an.l 
rise    while  the  gangue-minerals.  such  as  silica  and  limestone,  .■emain 
in  the  luiui.l  where  they  can  be  .liseharge.l  as  tailing 


•Jl^ 


11 H.    H.nl'  MIoN     li((M  |» 


DISPOSAL   OF    FLOTATION   RESIDUE 


SiiKi.i.si{i;\i( 

■iilifi'    /'/-i-.vs  of  llf<(  IllbtT  11.   H»l.'>) 


*  In  TUiiin  CI  KIN.  'I'lirff  ^iif  many  nu'tlMids  ul'  liiiiuUiiif^  siiiid  and 
<h\\u'  Innii  iiKtalliiru'iial  (i|)cratiiins,  Imt  in  tliis  artiidi'  the  draiiiitis; 
and  cnnvcvinir  nf  wasli'  |)roi|nrts  fnini  Hotatioii  processes  will  be 
spri'ially  dialt  with,  tln'  nitthiids  j;ivcn  Iwin';  tlmse  in  us»>  at  the 
leadinir  tlotatinn  plants  in  Australia. 

DiMiNiNii  \Ni)  Diw  \ri:i!iNi:.  It  is  generally  advisalile  to  tlior- 
iput;hly  diwatcr  the  risidne  t'nini  flotation  treatment  in  order  to 
form  a  elo.sed  eireuit  of  liipior.  This  maintains  constant  conditions 
throufi^hoiit  the  plant  and  avoids  waste  of  oil,  which  woidd  he  carried 
away  hy  the  soliilioii  with  the  tailiti?.  The  methods  that  may  he 
used  for  this  puri>o.si'  are  : 

(a)  Filterintr  in  vats;  ih  eondjination  of  a  suhmerfjeil  drainiiiE:- 
iielt  and  Dorr  thii-keners :  id  comhination  i>f  Caldecott  diaiihratrm- 
coiies.  drainiiii;-helt,  and  Dorr  thicken«'rs.  and  (d'  comhination  of 
Dorr  classitiers  and  Dorr  thickeners. 

^''iLTEKiNO  IN  V.\TS.  In  tliis  system,  shown  in  Via.  r)0,  the  pulp 
from  flotation  is  run  direct  into  vats.  These  arc  u.stially  If)  ft.  diain.. 
their  depth  varyiiifr  from  10  to  'In  ft.  In  the  centre  of  each,  and 
hpfore  (illin?.  a  tuhe  or  pipe.  l'>  in.  diam.,  that  fits  over  the  eii'cnlar 
discharce-hole,  is  inserted.  When  the  vat  is  ready  for  emptying, 
this  tuhe  is  lifti-d  out  a  lartre  proportion  of  tlie  tailing  falling 
throiifrh  the  centre  hole  onto  a  conveyor  underneath.  The  remainder 
is  afterward  shoveled  upon  the  s,ime  conveycn-. 

A  wooden  frame,  in't  shown  in  the  sketch,  is  erected  above  the 
vat  to  support  the  liftinpr-ch'vice.  a  screw  block  being  used  +0  raise 
the  pipe  to  the  desired  height.  This  operation  is  afterward  carried 
out  by  an  ordinary  block  and  tackle.  The  vat  may  be  made  of  wood 
or  iron,  and  the  height  to  which  it  may  be  constructed  is  eontrolleil 
hy  local  ciindilioiis.  such  as  the  design  of  the  plant,  and  the  nature 
and  fineness  of  the  material  to  he  filtered.  If  is.  however,  appari'ut 
that  the  greater  the  height  that  can  be  ecoiiomicall.v  employed,  the 
less  fill'  labor  rcipiired.  as  a  proportionately  large  amount  drops 
through  the  centre  of  the  vat  withont  shoveling.  This  would  tend 
to  make  the  inner  tube  too  long  to  be  iianuied  eonvenienii.v,  hut  tiie 

•Abstract  from  Min.  and  Evg.  Review,  Melbourne,  AuPtralia. 


r)isr(isAi.  Ill    ii.oTM'KiN   UK.^ini  i. 


249 


dittii'iilty   has  been   ovcrcniiic   l>y   iiiakiiifj   tin'   tiiln'   in   sections,   each 
of  which  is  lilted  in  its  turn  I'roni  the  to|)  as  cMi[)tvini.'  proceeds. 

Tlic   time   of   tiltcrin^f   is   arrnnjfcd    accordiiifi   to   the    iiiiiiiher   of 
vats  ("ii|)loyed,  Iml   it   is  tiie  usual  [iraetiee  to  run  the  pidp  throuifli 


Fig.  49.     al'stbalian  boom-oimtbibutob.    uelt-dbive.n  witholt  oeab  at  900  n. 

I'KB  MIN.  IIV  SLOW  SI'K.Kl)  MOTOU  (O.NTBOI.LtU  KBO.M   BKI.OW.      TME   .MACHINE 
(AN    UK    .MOVED    WHILE    WOBKI.\(i. 


a   number   in    series,    so    that    the   slime   settles    from   the    solution. 

Tl....,     ;f    „;..    ,..■•,.    ..„ „     i.„      )__:,.: ..    i     „       ,i 
int=,     l!      -,•-■,      r::.-     ::••      :::     ::— .     •■::r     :::r.\      :,'r     ufitihillo     ;i:iU     aiiLi'tllLI" 

emptying,  while  the  remainder  would  he  used  for  the  .  .ilp  flowing, 
in    series,   througli    tiicm.      Tiic    filtered    water    is   carried   off   hv    a 


i;)(  1 


Till-:    FLOTATION    I'KOCESS 


number  oi'  pipes  at  the  bottom  of  each  vat.  I'luler  certain  eonditious 
a  suctiou-pmiip  is  eoiiiieeted  to  these  pipes  to  assist  tiie  tilteriug,  but 
this  is  lint  tlie  usual  practice.  As  a  filteriiig  medium,  cocoa-nut 
mattint:  is  used  freiicrally. 

After  a  \at  has  been  emptied,  the  tube  is  dropped  into  tlie 
discliargi-liole,  two  lugs,  one  ou  each  side  keeping  it  in  position. 
'I'lic  open  space  round  the  tube  is  then  filled  with  clay.  It  is 
ad'isable  to  have  the  bottom  of  the  vat  six  feet  above  the  ground- 
level  to  allow  of  easy  access  to  tlie  conveyor  underneath.  At  the 
spot  where  the  sand  is  discharged  upon  the  conveyor-belt,  guide- 
doors  are  arranged  parallel  witli  the  belt  to  prevent  -..uu]  going  over 
its  edge,  and  the  number  of  idlers  under  the  conveyor  is  increased 
to  pre\('iit  it  sagging  under  a  rush  of  feed.  The  conveyor  is  usually 
a  Hat  belt.  24  in.  wide,  traveling  at  :J5()  to  -0)0  ft.  per  minute, 
4-in.  iron  idlers  being  used. 

This  iiietbod  lias  many  excellent  features:  its  advantages  arc: 
(li  The  moisture  of  tlie  drained  tailing  is  less  than  in  any  other 
system:  '2!  the  slime  is  drained  at  the  stiiiie  time  Jis  the  sand: 
I  '■]  I  dams  for  handling  the  slime  and  the  cost  of  labor  or  same  are 
eliminated:  4i  dusting  troubles  are  minimi/ed  (ui  the  du  •.  owing 
to  the  slime  li'>'piiig  to  set  the  tailing;  (">)  the  angle  of  repose  of 
the  dump  is  increased,  thus  enabling  more  sand  to  be  stacked  per 
unit  of  ground-area;  (6)  no  trouble  with  conveyors  handling  tailing 
will  cause  a  stoppage  in  the  main  plant;  (7)  accurate  sampling  of 
l)roduets  is  possible,  enabling  shift-work  to  be  kepi  under  control. 

Tiie  disadvantages  are:  (1)  High  initial  cost  of  erection;  (2) 
iclatively  high  cost  nf  labor  in  emptying  vats;  (3)  clarification  of 
'.elutior.  is  not  usually  as  c(unplete  as  is  the  case  with  other  methods. 

('o.MBiN.\TU)N  oi  Drain  \(iK-HKi,T  ani>  Thickkners.  .  The  idea  of 
tiu'  suhiiierged  diaining-belt,  I  think,  was  first  intr  Jueed  in  connec- 
tion v.itli  the  Elmiu-e  process  in  order  to  overcome  the  difficulty  of 
discharging  the  residual  pulp  without  upsetting  the  vacuum  in  the 
flotation  apparatr.'  In  this  system  the  belt  runs  inside  an  iron 
troutrh  tilled  with  water,  being  forced  into  a  semi-circnlar  shape 
by  means  of  a  spherical  pulley,  a.s  shown  in  sketch.  Fig.  al.  The 
bi'll  travels  under  water  for  a  eertain  distance,  ri.sing  at  a  slope 
of  If)  to  20     onto  the  bead  pul'ey. 

The  rlrive  is  usually  from  the  tail-end  by  means  of  a  worm- 
wheel  on  tiie  tail  pulley  shafting.  This  tail-pulley  is  generally 
t)  ft  diam.,  and  is  faced  lui  iiie  outside  with  wooden  boards  to  give 
the  belt   a  better  r     ?■     The  fe^d   is,  preferably,  distributed  to  the 


DISI'OS.VI.   OF    I-I.OTATION    KKSIDIK 


251 


belt  by  means  of  an  iron  laiuider  with  holes  in  the  bottom,  wooden 
guides  being  arranged  to  guard  against  sand  getting  betwm  the 
under  side  of  the  l)elt  and  the  trough.  The  trough  has  side  iders 
attached  to  carry   tiie  overflow  to  Dorr  thickeners,  the  number  of 


(E 


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the  latter  depending  on  general  conditions,  such  as  nature  of  slime, 
amount  of  water  in  circulation,  etc.  The  submerged  belt  forms  an 
excellent  desliming  system,  by  reason  of  the  classitication  in  the 
trough:  its  capacity  is  4000  or  more  tons  a  week  of  mixed  slime  and 


TIIK    II.CTATKIX    I'liOCKi 


s.iii(l.     The  (h-aiiiiiig  of  tlie  saml  is  ac('i)iiii)lislRHl  as  it  risvs  I'rom  the 
siirt'ai-c  <it'  tile  li(|uia  i,i  ilir  troii>,'ii  to  tli»>  liead  pulley. 


■//'WUXL^Cir^: 


ctiiiiloycd.     This  coiisists  of  an  idler  driven  by  two  eeerntrics.     The 
vihration    eaused   on    the   helt    hy   the   idler   striking   it   underneath 


nisposAi,  OK  n.OTATiox   u;:sri)i  i; 


2.3;i 


displaces  a  larger  quantity  of  water  from  the  Siiml,  and  thus  reduces 
the  proportion  of  moisture  in  the  final  product.  An  iron  scraper  is 
used  t'o-  removing  the  tailing  from  the  draining-belt ;  it  may  he 
kept  lender  pressure  by  means  of  iron  springs.  This  method  is  very 
good,  especially  where  the  room  available  for  drainage  is  limited. 
It  is  also  convenient  where  the  height  of  the  flotation-plant  above 
the  ground  is  small. 

The  life  of  the  belt  is  less  than  that  of  an  ordinary  draining-belt, 
owing  to  the  heavy  pressure  of  the  spherical  roller,  and  the  action 
of  the  hot  circuit-liquors  in  which  the  belt  is  sul)nierged.  The  labor 
for  attendance  is  small.  This  method  is  at  present  in  us(>  on  two 
of  the  large  flotation  plants  at  Broken  IIiil. 

COilBINATION    OF    CoNKS,    DRAININr.-Hla.T,    A.NI)    TlIICKENERS.       TIlis 

method,  diagrammatically  illustrated  in  Fig.  ')2.  has  been  installed 
in  the  latest  rtofation-plant  at  Hroken  Hill.  The  size  of  the  Caldceott 
cones  usually  employed  is  12  ft.  diatn.  and  10  ft.  deep,  the  diaphragm 
being  2  ft.  to  2  ft.  6  in.  from  the  bottom  of  the  cone.  In  most  cnscs 
a  plate-diaphragm  is  used,  but  the  introduction  of  an  iron  ball  to 
serve  the  same  purpose  has  been  most  sneeessful.  Where  a  cone  of 
this  type  is  used  as  a  thickener,  rather  than  as  a  slime-cla.ssitier, 
more  pulp  may  be  thickene<l.  as  the  height  of  pulp  need  not  ))e 
so  finely  adjusted.  Still,  it  is  custemary  to  keep  the  level  of  the 
Siind  two  feet  from  the  top  of  the  cone,  as  measured  in  the  centre. 
The  feed  usually  passes  into  these  cones  ihrough  a  centre  of  the 
Callow  type. 

To  remove  the  thickened  pulp  continuously  iiiid  divert  it  onto 
the  dniining-belt,  an  ordinary  plug  nny  be  u.sed  with  advantage, 
provided  coarse  rubbish  has  be-'n  removed  previously.  Another 
successful  device  is  a  plug-valve  or  a  plug  worked  from  the  top. 
fitting  into  a  seat  at  the  bottom  of  the  cone.  The  type  of  draining- 
belt  employed  i.i  -Hi  in.  wide.  The  belt  rises  gradually,  about  1  in  60. 
from  the  tail-pulley,  the  la.st  .W  ft.  of  the  slope  being  increas<'d  to 
about  20°.  The  belt-speed  is  20  to  ,30  ft.  per  min.,  both  ordinary 
and  troughing  idlers,  of  fi-in,  diam..  being  used.  As  the  operation 
of  the  belt  is  slow,  wooden  idlers  working  'n  ca.st-iron  'dead-eyes' 
can  be  successfully  u.sed  for  the  horizontal  idlers,  the  troughing- 
idlers  being  of  the  usual  type. 

The  drivo  is  at  the  head  end.  double  gearing  for  speed  reduction 

)^.-.!>ifv    p.,^n1. .«,.,.]  Til,  „     \ 1    II...     ;  11         ,.     ,«.         ,. 

^   *. -rTj.*:-'-' M.       1  ::r  ::--;i;i  ];;:i:i';,-    is  gCiUTauy  ,")   Ti.    iiiaiVi.,    liie   .sjilii'- 

pulley  18  in.  diam..  and  are  of  contact  200  to  2.')0°.  The  tail-pulley 
is  usually  2  ft.  diam.     Hnbber  belting  on  the  face  of  these  pulleys 


TIIK    l-I.OTATIdN     l'R()CK> 


lediK'i's   the    slip,    tlic'rt'l)y    iimreasiiif,'    the    power-efficieiicv   ami    the 
life  of  the  helt. 

The  overflow  from  tiic  C.ildeeott  cones  goes  into  one  or  more 
Dorr  thiekenci-s,  aeeoniing  to  reciuirements,  the  underflow  from  the 
thiekeners.  as  in  other  methods,  hein?  handled  with  flooded  sucti.in- 


i'liinps.  Att.iiipts  to  mix  tiie  underflow  from  the  Dorr  thiekener 
with  pulp  on  the  drainiufz-belt  in  order  to  convey  lliem  together  to 
the  pump  have  not  so  far  i)roved  sueeessful.     For  the  eontrol  of  the 

undi-rflow   frnni   Dorr  thick'-'j-ers  the  hv:lr.".;:i:.(-aT-  ;-.-..-.! !..-..!    /.i _;i     : 

in  'Hand  Mctallurgieal  Praetiee')  has  proved  quite  satisfactory,  "a 
ronstant   pulp,   with    Hrokoi    Hill  slime   of  50%   solid   being  ea.sily 


|il-.|'i)SAl.    OK    KLUTATIMN     KK^IDrK 


iiiaiiitaiiu'd.  This  iiietlioil  is  coiisido red  a  good  one,  hi'i^ausc  the 
<'()st  of  lal)or  is  h)\v,  the  life  of  tlie  draiiiiiig-belt  is  prolonged,  anil 
the  tost  of  inaintenanee  is  small.  Aiieriuate  head-room  is.  liowevcr. 
neeessary  for  tiie  erection  of  the  cones;  in  some  eases  elevation  is 
essential.  A  disadvantage  is  that  a  stoppage  of  the  dump-iielts  causes 
a  stoppage  of  tiic  whole  plant. 

CoMBiNATio.N  OF  Classifikks  AND  TuicKKNKifs.  Tills  method  has 
not.  to  my  knowledge,  yet  been  adopted  at  any  plant  in  Australia, 
but  the  great  success  that  it  has  achie'-ed  at  cyanide  plants  in 
America  shows  that  it  rould  be  applied  to  the  handling  of  tailing 
and  slime  products  at  Broken  Hill.  The  usual  type  of  Dorr  classifier, 
however,  would  have  to  lie  especially  lengthened  to  cause  e.xtra 
draining  of  the  sand  product.  Owing  to  the  regular  working  of 
these  machines  the  usual  draining-belt  may  be  discarded.  At  the 
.same  time  very  little  head-rooin  would  be  required.  This  method 
is  illustrated  in  Fig.  53.  which  shows  the  classiliers  delivering  din  rt 
onto  the  inclined  belt.  It  has,  however,  the  same  di.satlvantage  as 
the  method  last  mentioned,  in  tiiat  it  does  not  make  the  trcatuicnt- 

plant  independent  of  the  dump-belt  stoppages.     The  cost  of  ei tion 

and  maintenance  would,  however,  be  small. 

IlAxm.i.NO  OF  Drained  I'lioDicTs.  Tailing  may  lie  handled  in  the 
following  ways:  (a)  Inclined  conveyor-belts  and  boom-stackers,  (b) 
aerial  trams,  (c)  tnieking.  and   (d)  sluicing. 

In'cmnei)  Conveyou-Rf.it.s  and  Room-Stackers.  The  usual  angle 
for  an  inclined  conveyor  is  20  ;  where  possible  the  conveyor  sliould 
be  driven  from  the  head-end.  Where  the  head-end  is  high  above  the 
ground,  the  drive  shoidd  be  either  from  the  tail-end  or  from  ,i  large 
centre-i)ulley.  midway  along  the  belt,  having  a  sinili-pnlley  at  each 
side  above  it,  the  ceiitrc-pidley  being  0  to  8  ft.  diam.  and  resting, 
preferably,  on  a  concrete  base. 

The  inclined  conveyor  is  first  of  all  built  on  trestles  at  the  angle 
required.  As  the  size  of  the  dump  increases,  the  conveyor  is 
•■.xtended  in  the  form  of  a  cantilever,  held  bv  guy-ropes  from  the 
upright  trestles  in  the  dump.  A  belt  to  handle  40  to  50  tons  per 
hour  would  require  to  be  one  of  24  in.  six-ply  rubber  Iniilt  on  3  to 
10-in.  .stringers,  placed  .1-ft.  centres.  If  driven  from  the  head-end. 
the  driving  pulley  should  be  5  ft.  diam.  gear-driven,  the  tail-pulley 
being  2  ft.  diameter. 

The  AuF.trHlian  r^r'ictiee  is  to  use  .*5/^*^firMt"  ?";il!;-- .;  :*Tiil  tr.-.:-jrt-.;T-~ 
idlers  instead  of  a  combination  idler.  This  practice  is  simple;  the 
idlers  enn  be  more  easily  lubricated.     The  best  size  of  roller  is  4  in. 


2Mi 


iiii;  ii.o'rviiiiN   liioci:: 


diain.  Jt  is  usually  iiuult,'  of  stt'cl  pipe  shiuiik  onto  cast-iron  i-nil 
pieces.  A  favorite  practice  is  to  have  idlers  and  dead-eyes  on  the 
top  of  the  same  striufiers.  the  loaded  and  return  belt  running  on 
rollers  supported  by  the  same,  and  liejnj,'  ai)out  three  inches  apart. 


The  toj)  rollers  are  usually  spaced  4  to  (J  ft.  centres,  the  return  idlers 
being  S[),iced  at  twice  this  distance  apart.  Wooden  rollers  for  fast 
belts  of  this  tyi)e  are  not  satisfactory. 

In  ealcul.'Miig  the  power  required  for  this  type  of  belt  it  is  well 


Disi'osAi,  (IK  h'i,(rr\rii).\   ni>ii)rK 


257 


to  rtMiitMiilxT  that  tlie  liorsrpowcr  lost  in  friction  per  !0(l  It.  varies 
iiivcrst'ly  as  the  Icngtli  of  tiic  belt,  avcniffiiiK  from  2  to  ti  lip.  per 
100  ft.  A  tifihteiiiiis  arraiiKi'ineiit  is  usually  fixed  on  the  tail-i)uUey 
of  this  type  of  l)flt  to  cause  it  t.)  run  true  and  take  up  any  unneces- 
sary slack.  When  an  inclined  conveyor  luus  heen  carried  out  to  an 
eeonomical  distance,  the  tailing  at  its  end  is  made  into  a  hed  for 
a  hooin-stacker.  This  is  an  iron  pole,  which  is  held  in  position  by 
four  strong  guy-ropes.  Attiiclied  to  the  pole  is  an  iron  lattice-girder, 
which  is  supi^irted  similar  to  a  oanliliver  hy  guy-ropes  attached 
to  the  pole  itself.  This  hooin  stacker  resis  on  a  steel  ball  in  a  cup- 
shaped  receiving  device,  which  enables  it  to  swing  around  as  desired. 
Tlie  weight  of  the  boom-stacker  is  spread  over  a  large  .irea  by  means 
of  a  number  of  heavy  timbers  resting  in  the  prepared  foundation 
on  the  dum().  The  conveyor  on  the  boom-stacker  is  driven  by  a 
motor  fixed  liehind  the  boom,  and  traveling  around  with  it.  [The 
]iliotograph  (F^ig.  4!t)  shows  a  good  boom-stacker  at  Kalgoorlie. 
Western  Australia,  from  which  place  th(>  Hroken  Hill  system  was 
largely  copied. — Editor.] 

Akki.vi,  Tk.\.\is.  These  are  so  well  known  that  they  need  no 
description  here.  For  moderate  tonnage  they  are  seldom  used,  as  a 
bin  is  required  and  two  men  loading  and  operating  trucks. 

Handling  ok  Slimk.  The  pulp  from  Dorr  thickeners  is  either 
transferred  by  flooded-sucticm  centrifugal  pumps  or  three-throw 
l)umps,  or  else  elevated  by  an  ordinary  belt-elevator.  Where  there 
is  room  for  a  slime-dam  cloS(>  to  the  treatment-plant,  the  belt-elevator, 
which  is  a  very  economical  system  of  elevation,  may  be  used.  In 
other  eases  centrifugal  pumps  are  resorted  to.  The  thickened  pulp 
may  also  be  delivered  to  dams  or  sprayed  onto  the  surface  of  sand- 
dumps.  To  remove  the  drained  water  it  is  preferable  to  u»»  a  wooden 
box-launder.  This  consists  of  two  box-launders  eonnected  in  the 
form  of  a  right  angle,  and  fi.xed  in  position  at  the  starting  of 
the  building  of  the  dam.  The  horizontal  portion  of  the  launder 
is  laid  12  ft.  inside  the  dam,  and  is  carried  to  the  water-sump 
outside  it.  The  vertical  portion  passes  through  the  slime  and  is 
bored  with  holes,  which  are  plugged  from  the  bottom  upward  as 
the  building  of  the  dam  proceeds.  Probably  the  best  method  of 
handling  slime  pulp  is  to  pump  it  through  a  nozzle  onto  the  surface 
of  sand-dumps.  By  such  means  it  may  be  sprayed  evenly  all  ovt  r 
tne  •luiup. 


^lis  itiirs  away  witij   (.i^Tiii 


ciUTKo  ii:c 


1   rising 

from  the  sand-dump.     The  idea  was  first  originated  in  South  Africa, 
and  has  onlv  latelv  l>een  introduced  into  Australia. 


2ris 


Tin;  Ki,iir\Ti()\   I'nocKss 


THE  ELECTRICAL  THEORY  OF  FLOTATION-II 

By  Thomas  M.  Bains,  Jr. 

(From  the  .Viiting  anil  Srirntiftc  Pnss  of  December  11.  lai:,) 

TIk'  article  in  tlif  MiniiKj  and  Scuntific  Press  of  October  23, 
inio,  hy  Mr.  (),  C.  HiiNt„M,  liMs  lirnu^'lit  out  inaiiy  jx.iiils  of  interest.' 
It  .seem.s  to  me,  liouev.  r.  that  the  fundamental  prineiples  of  flotation 
ran  best  he  stndi.^d  witli  hirjier  particles,  thus  avoiding;  the  interesting. 
Init  also  little  undestood  'eolhud'  ehemistry.  In  jjravily  separation 
l»y  rising  currents  of  water,  Rittinger's  formula  V^c\':  i^Z) 
liol.l'-  true  for  i)artirl,.s  above  a  certain  size,  naiuelv,  about  O.L'  iinn 
for  (piart/,  and  O.VA  mm.  in  case  of  galena.  Below  the.s,.  sizes. 
colloidal  and  other  little-known  phenomena  become  of  importance 
and  comi.liiate  the  investigation.    So  it  is  with  flotation. 

In  the  laboratory,  it  is  pn.ssible  to  use  larger  particles.  The 
following  experiments  were  conducted  in  the  Case  School  of  Applied 
Science  on  material  sized  through  20  and  ;jO-me.sb  screens.  The 
phenomena  connected  with  ]>r.>ferential  flotation  furnish  new  eviilence 
to  strengthen  the  electrical  theory. 

The  simplest  experiment,  demonstrating  preferential  flotation,  nuiv 
be  performed  as  follows:  Upon  a  4-incli  wateh-gbuss.  place  a  little 
galena,  blende,  and  quariz.  of  20  to  ;50-me.sb  size.  Add  dilute  „it,ie 
acid  and  place  the  gla.s.s  under  a  mi.sero.scope.  The  acid  attacks  the 
galena,  fitrming  bubbles  of  II_,S  gas  that  adhere  to  the  galena.  The 
particles  of  galena  are  electrified  also,  as  can  be  seen  by  the  actions 
of  the  pariicl.'s.  The  bleulo  and  quariz  are  not  attacked.  If  the 
ore  had  been  finely  pulverized  and  dilute  nitric  acid  added,  the 
bubbles  of  IIS  would  have  been  sutificient  to  float  the  galena,  leaving 
the  blende  and  quartz  at  the  bottom.  However,  with  fine  particles, 
some  blende  and  quariz  woulu  have  been  entrapped,  brought  to  the 
surface,  and  held  there  by  surface  tension.  The  bubbles  are  not 
sulTicient  to  float  the  coar.se  galena,  bn^  by  a  vanning  motion  of  the 
gla.s.s.  the  galena  will  collect,  being  brought  an.l  held  together  by 
the  II.,S  bubbles,  forming  a  mat,  which  =s  lighter  than  rpiariz  or 
blende  and  can,  therefore,  be  painied  of?',  leaving  the  blende  and 
qnartz.  This  experiment  seems  to  show  Miat  the  H.S  is  charged 
oppositely  to  the  galena. 

i:  rr.orc  .  oi,,  oiitiHi.  .i  luini;  acid  iia  i  been  added  to  the  ore, 
the  blende  would  have  been  attacked  an.l  the  process  would  have 
been  revei-sed,  the  blende  forming  the  mat  while  galena  and  quartz 


Tin;   KI.KCTKICAI.  TllKOKY  OK  KIAJTATION  —  II 


25!) 


"fie  left  lieliiiid.  If  dilute  sulphuric  acid,  one  part  of  acid  to  four 
of  water,  had  been  used,  then  both  the  l)le!idc  and  galena  would 
have  been  attacked  and  if  the  ore  had  been  finely  pulverized,  no 
'preferential'  wparatiou  would  have  resulted,  both  galena  and  blende 
lindiiit;  their  way  into  the  float  concentrate.  However,  with  coarse 
material,  the  blende  is  much  more  highly  charged  than  the  galtr.a 
and  if  the  watcii  gla.ss  be  tapjied  ami  the  contents  given  a  vanning 
motion,  the  blende  will  gather  most  of  the  ILS  bubbles  and  finally 
float,  leaving  galena  and  ([uartz  behind.  This  shows  that  the  elee- 
trilication  of  minerals  varies  with  different  acids  and  also  with 
different  strengths  of  the  sjime.    This  action  of  one  mineral,  'robbing' 

liic  otiii'is  of  ihcir  bubb!(s.  has  not  I n  utilized  in  practice,  as  yet, 

but  there  is  no  reason  why  'preferential'  separations  could  not  be 
made  on  a  large  scale,  utilizing  this  principle.  Less  air  or  gas 
would  be  necessary  than  in  the  present  type  of  frothing-cells  and  a 
clean  concentrate  would  be  produced  at  ofice.  A  separati.m  of 
blende,  galena,  pyrite.  and  quartz  may  be  made  as  follows; 

Add  dilute  sulphurc  acid  and  pan  off  the  blende;  then  add  dilute 
nitric  acid  and  pan  off  the  galena;  then  add  concentrated  sulphuric 
or  nitric  acid,  which  attacks  the  pyrite  so  that  it  may  be  panned  off. 

Or  the  separation  may  be  made  with  nitric  acid  alone,  varying 
the  strengths;  with  sulphuric  acid,  by  use  of  the  'robbing'  action 
described  above  or  by  use  of  hydrochloric  and  other  reagents  that 
attack  one  or  another  of  the  minerals  more  strongly  than  the  others. 
If  galena  or  blende  and  magnetite  be  treated  with  dilute  sulphuric 
acid,  the  magnetite  will  not  be  acted  upon  by  the  acid,  but  some  of 
the  n._,S  bubbles  generated  by  the  sulphide  will  attach  themselves  to 
the  magnetite,  provided  the  bubble  is  formed  near  the  magnetite. 
This  illustrates  the  fact  that  eVctrical  conductors  in  a  conducting 
liquid  attract  electrified  bubbles.  A  slight  jar,  however,  will  displace 
these  bubbles;  or  a  piece  of  sulphide  in  close  proximity  will  rob  the 
magnetite  of  the  bubble,  magnetite  being  a  poor  conductor. 

Referring  U)  the  article  on  page  668  of  the  Mining  and  Scientific 
Press  of  October  -SO,  1015,  describing  a  patent  for  preferential 
flotation  of  blende,  galena,  and  pyrite,  the  second  paragraph  reads: 
"The  new  process  consists  of  treating  ores  in  a  medium  (».  e.  sulphuric 
acid  and  sodium  sulphite)  that  wets  the  zinc  sulphide  and  which  does 
not  wet  the  lead  sulphide  or  pyrite."  This  phenomenon  brings  out 
liiiciv  tnc  pari;  piayiCi  in  noTatioii  Dy  tiie  ""  Jieit-otiic  iiim. '  VV  iien 
thio-sulphates,  sulphites,  or  bi-sulphites  are  acted  upon  by  sulphurii- 
aci<l,  there  is  more  to  the  phenomenon  than  formation  of  SO,  gas 


•jno 


'INK    H.olv  TIciN    I'KciCKss 


Til,"  following'  iva.'lioiis  takf  ph \vli<.|i  l,|,.|i,|,.  iiixl  i:n\nui  ar.'  tnate.l 

with  siili)liurii>  add  aiwl  sodiiirii  snlpliidc  : 

;^ms  4-  I'lis  f  L>ir,s(),r..znSo,  +  im.so,  +  l>h,s 

•Xa,S()^  -f-  ir,S().  -.-  Na.SO.  +  II,,()  +  SO,   " 
;2H_S  +  S()_,^.2IL()   f-;iS 

'I'liis  .sulplnir  tlms  fonii.d  is  in  a  vory  tine  staff  iuid  ads  as  a 
di.'l.M.tric  film  about  flic  (?al."im.  for  which  if  l,a.s  a  nrvnt  attraction. 
Therefore,  no  frofhinp  a(j,  iit  is  nccd.'d  in  this  case,  as  tiie  dieh-ctric 
til  1  al.onf  the  hiihhles  is  formed  l,y  the  sulphur  similarly  to  the 
films  of  oil  formed  in  the  ordinary  flotation  processes.  In' the  last 
paragraph  of  the  ahove-menfioncd  arfi.d.'  on  'Preferential  Flotation.' 
the  .statement  is  made  that  "the  procuring  of  the  efTect  aimed  at.  is 
dependent  upon  the  presen-e  of  a  frothinj;  anenf.  onl,/  when  a 
reducing  „,,s  is  intro<h(,,d  info  the  me.lium.  If  is  not  depeiul..nt 
on  the  presence  of  a  frothing  agent  in  the  flotation  medium,  when 
a  reducing  gas  is  (joh  ruled  in  the  flotation  medium  l.y  a  reaction  of 
a  substance  introduced  into  it."  In  other  words,  if  sulj.hur  or  anv 
other  'dielectric'  is  liberated  in  a  very  fin.,  state.  l)y  a  "rea.'fion  oV 
a  .Mib,>,taMce  introduced,"  no  frothing  agent  need  be    ised. 

This  action  nuiy  be  nicely  illustrated  by  faking  20  to  ;JO-mesh 
galena  an<l  blende  and  treating  them  with  dilute  nitric  acid  on  a 
watch-glass  and  observing  the  result  under  a  microscope.  The  galena 
will  gather  all  the  II.S  bul)bles.  when  vanned.  Now  if  the  snlpliurio 
acid  is  added  and  the  watch-gla.ss  be  tapped  and  the  particles  moved 
over  one  another,  the  IL.S  bubbles  on  the  galena  will  l)e  robbed  by 
the  blende.  Sulphur  may  be  seen  .surrounding  the  bubbles,  fh.e 
reaction  being  as  follows: 

ZnS  +  PbS  +  2ir,S0,  =^  ZnSO,  +  PbSO,  -f-  2II.,S 

(1)  n,S  +  ILSO,  =  SO,  +  2II..0  4- S 

(2^  2ILS  +  SO,  =  2H,0 +'3S 

In  (I),  the  sulphur  is  formed  from  the  decomposition  of  ILS : 
and  would  be  charged  oppositely  to  the  sulphur  formed  by  the 
decomposition  of  SO,  gas.  In  i2).  we  have  both  ucgatively  and 
positively  charged  sulphur  particles. 

The  larger  bubbles,  with  sulphur  particles  adhering  to  them,  may 
burst  on  reaching  the  surface  and  their  film  of  sulphur  wJH  spre.id 

•Newth'8  'Inorganic  Chemistry,'  p.  417. 
jlbid..  p.  436. 


TlIK   KI.KCTKIC.M,  TIIKUKY   i)K   H/)TAT|U\  —  II 


261 


over  the  water.  If  jjarticlfs  of  ininernl  had  Ix't-n  attracted  to  the 
bubble,  then  tli.sse  partid.-s  woiibl  have  remained  attaehed  to  the 
sulphur  tilin,  even  after  <li.sruption  of  the  bublile.  sliouinj,'  lh<'  eleetri- 
tieatioii  of  the  dieh'etric  (ilm.  Tlie  same  pheiioip.enoii  occurs  wlieii 
the  tihii  is  a  li(|uid  dielectric,  like  oil. 

The  laboratory  tests  with  eliemieal  reagents  generating  IIjS  gas 
give  the  opposite  resultn  from  the  regular  air-bubble  flotation.  The 
ordinary  HoUition  method  in  practice  is  to  add  a  litth'  acid  and 
frothing  agent  to  the  pulp.  The  sulphides  are  positively  charged  by 
friction,  while  the  frothing  agent  and  air  are  ehargec!  negatively. 
The  oil  8urn)uiuls  the  8uli)hides,  but  the  film  is  so  thin  that  the 
negatively-eharged  bubble  is  attracted  by  the  positively-charged 
sulphide.  If  the  film  of  oil  is  too  thick,  the  attraction  between  the 
sulphide  and  bubble  is  too  feeble,  and  flotation  fails. 

In  the  laboratory,  ILH  is  charged  positively,  but  the  sulphides 
are  charged  negatively  by  chemical  action.  So  the  bubble  attaches 
itself  to  the  electrified  sulphide. 

In  preferential  flotation  of  galena  and  blende,  in  practice,  the 
ore  is  treated  with  II.SO,  and  Na.,SO,,,  Sulphur  is  liberated  and 
the  galena  is  coated  with  the  particles  of  sulphur  positively-charged, 
while  the  negatively-charged  sulphur  coats  the  gas  bubbles.  The 
negatively-eharged  air  bui)bles  of  the  flotation  machine  attach  them- 
selves to  the  positively-charged  sulphur  coating  the  galena  and  repel 
the  negatively-charged  blende. 

In  the  laboratory  experiments,  the  II,,S  bubbles  are  charged 
positively  and  are  attracted  to  the  negatively-charged  blende  and 
repelled  by  the  positively-charged  .sulphur  on  the  galena.  In  this 
ea.s.',  the  blende  is  floated.  When  ILS  is  l)lown  into  the  pulp  in 
practice,  no  sulphur  is  formed— the  II.SO,  .solution  being  too  weak 
for  this  reaction.  Therefore,  to  make  a  pei-sistent  froth,  a  frothing 
agent  must  be  added  to  the  pulp. 

In  conchLsion,  it  may  be  well  to  call  attention  to  the  fact  that 
for  laboratory  experiments  in  preferential  flotation,  any  one  of  the 
sulphides  may  be  s«'parated  from  the  other  sulphides,  (o)  by  the  use 
of  some  reagent  that  attacks  this  particular  sulphide  and  not  the 
others,  (b)  by  the  use  of  a  reagent  that  attacks  one  -sulphide  moi-e 
vigorously  than  the  others;  in  this  ca.se.  the  vanning  motion  allows 
the  sulphide  more  highly  charged  to  gather  up  the  bubbles  from  the 
Mii|>iiiues  less  iiigtily  ciuirged,  and  if  sutticient  bubbles  are  collected, 
the  ma.s.«  of  bubbles  and  sulphide  will  float.  If  not  sufficiently  buoyed, 
the  mass  remains  submerged,  but  it  is  lighter  than  the  other  sulphides 


.>«2 


TIIK    KI.OI'ATION    I'KOCKSS 


or  KaiiKiif  innicrals  and  ran  !»•  paiiii.'d  .iff  or  Sfparutod  hy  liydraidic 
c'lassitication. 

Till'  .si'fomi  point  (if  iiitcr.sf  is  llic  formation  of  a  frothing  a^f.-nt, 
uitliin  till'  [ndf,  when  reactions  take  plan'  thai  liherate  (iiolei;trif 
siilistanns  in  a  very  fine  state,  flcctrically  diarjrod. 

The  third  point  is  tliat  hihoratory  rxpcrinicnts  may  not  work 
out  in  i)ra('ti(:(',  duo  to  failure  to  understand  the  nature  of  the 
eleetrieal  charKes  of  the  liuhl.les.  dieleetrie.s,  and  particles  of  ore.  A 
little  stroiijfer  reagent  or  a  different  way  of  frietionally  ele('trifyinn 
the  l.iilihles  and  pulp,  or  too  tliiek  a  film  of  dieleetric  or  frothing 
assent  causes  the  altraction  to  cease  or  change.  It  is  no  wonder  that 
UTcat    ditTicuIty   has   lieen   experienced    in    the    practical    application 

"•'  flotation   t -es.    wjien   such   delicate   electric    forces   have   to   !«> 

considered. 


'-'J 


KKKKirr.S  OK  SUM  HI, K  CUM  CDS  K.VIS  oK  OKK  ON    H.(>T\T|i>N 


•nv.\ 


EFFECTS  OF  SOLUBLE  COMPONENTS  OF  ORE  ON 
FLOTATION 

By   ■  N  Occasional  Cokkespondent 
(From  the  Mm.   j  and  Snrnlifl,'  I'r.ss  of  December  IK.  liti&i 

III  concentration  by  rtolalion,  tin-  s..liil,K:  components  of  an  ore 
may  play  an  important  .-ole.  Occasionally  ores  that  are  shown  by 
preliminary  test  to  be  unsuitable  for  flotation  may  be  treated  by  the 
process  after  the  soluble  ingrediei.  have  been  removed  by  decan- 
tation.  On  the  other  hand,  e.xcellent  results  may  be  obtained  on 
certain  ores  by  flotation  in  fresh  water;  but  when  the  water  is  fouled 
by  successive  contact  with  fresh  lots  of  ore  (as  is  often  the  ea.SH 
m  mill-practicej   the  results  may  be  far  from  satisfactory. 

This  article  deals  with  a  determination  of  the  fouling  agents 
m  a  cerUin  ore,  and  outlines  methods  for  overcoming  such  fouling 
efforts.  Since  all  tests  were  made  on  ore  from  a  single  mine,  the 
results  cannot  l)e  regarded  as  generally  applicable;  however,  it  is 
hoped  that  the  experience  recorded  here  may  be  of  some  interest 
to  others  studying  similar  problems  in  flotation. 

The  tests  were  made  on  a  silicificd-rhyolite  ore  assaying  silver 
37  oz.,  gold  0.15  oz.,  lead  1%.  copper  0.25%,  and  zinc  1.5%.  The 
principal  minerals  were  argentiferous  sphalerite,  argentiferous  galena, 
and  stromeyerite.  The  value  lay  almost  entirely  in  silver.  For  this 
reason,  only  silver  assays  are  here  recorded.  Suflficicnt  analyses 
were  made  to  indicate  that  the  concentration  of  zinc,  lead,  "and 
copper  roughly  paralleled  that  of  silver. 

Preparatory  to  making  the  tests,  a  large  general  sample  of  ore 
was  ground  to  pass  a  200-mesh  screen,  and  thoroughly  mixed.  In 
each  test,  a  200-gram  portion  of  the  general  sample  was  emulsified 
with  one  litre  of  water  and  0.05%  of  crude  pine-oil.  The  mixture 
was  then  treated  for  a  half-hour  in  an  experiment^il  flotation  machine, 
consisting  of  an  agitation-chamber  connected  in  such  a  manner  with 
a  concent rate-.separation  chamber,  as  to  permit  of  repeated  treatment 
of  the  tailing.  Kesults  in  a  flotation  plant  treating  this  ore  roughly 
checked  the  work  in  the  experimental  machine. 

Preliminary   tests  showed   that   when    the   ore   was  treated   by 

flotation   in  fresh  w.ater.   thp  tniiirii?  saa"vA.-;   n  .-.-     .-.! j   iJ- 

concentrate  assayed  440  oz.  per  ton.  When  the  water  used  in  the 
first  test  was  removed  by  filtration  and  re-used  on  a  second  test, 
the  tailing  assayed  18.  oz.,  and  the  concentrate  240  oz.     When  the 


264 


TIIK    II.OTATIO.V    I'muKSS 


satnc  Wiitcr  was  re-iis<.i  a  iliinl  time  on  a  fivsli  saiiii)lf  of  or.',  tlif 
failing'  assay.'.l    27   oz. ;   tlie   conceiitratf,    1!»()   o/.      Kvi,lriitly   sonic 

fxtiviucly   (IcIftiTious   siilistaiices   had   been   dissolved    t'rom    tl re. 

An  analysis  was  ..lade  of  tiio  water  filtered  from  llie  tliinl  test,  uitii 
the   following  results: 

Iron  (ferric)    y.^. 

Iron  ( lerrous  I         0  00"' ' 

Aluminum    -r- 

1  r. 

Caliiiini    v-i. 

Magnesium  oxide 0  01'"  ' 

Sulphur  O.02o4 

Manganese    !o!o01% 

Potassium  and  sodium   ,1  oiO'; 

Copper ^i. 

Most  of  the  soluble  miiierals  were  present  as  sulphates. 

The  next  step  was  to  delerinine  the  effeet,  on  flotation,  of  the 
various  sul[)hates. 

Sodium  and  potassium  suli)liati'S.  when  added  to  fnsh  tests  in 
the  proj)ortion  iiidieated  in  the  analyses,  yielded  a  1;{  o/.  tailint;  and 
a  (i;)0  oz.  eoneentrate:  thus  producing'  a  marked  inerease  in  tin'  <.'rade 
of  eoneentratf  without  detrimental  .ffect  on  the  tailing'. 

Manganese,  magnesium,  and  ferric  sulphates  produced  no  effect 
when  added  in  tlic  proportions  indicated;  in  larger  amounts,  mag- 
nesium .suli)hate  was  lia.mfiii  and  ferric  sidi)hate  beneficial. 

Ferrous  snlpliatc  proved  extremely  injurious  to  flotation.  When 
present  as  abovi'  recorded,  a  20  oz.  tailing  and  a  240  oz.  I'onccntrate 
were  produced.  When  a  small  amount  of  copper  sulphate  was 
added  to  the  same  (piantity  of  ferrous  sulpliate.  the  tailing  a.ssayed 
2.")  oz..  and  tile  concentrate  200  oz.  Evidently  ferrous  aii.l  copper 
suli)liates  were  the  prinei])al  fouling  agents  in  the  original  tests. 

It  was  neces.sai'v  to  devi.se  means  for  correcting  the  etVects  of  Miese 
sulfiliates. 

First  :  sutiMcient  sulphurie  acid  and  hydrogen  peroxide  were  added 
to  a  ciiarge  containing  ferrous  sulphate  to  I'onvcrt  the  ferrous  sulpliate 
to  the  ferric  state.  The  tailing  from  this  eliarge  as.sayed  11  oz.,  and 
the  concentrate  SOO  oz,  With  the  sa,.,.  amount  of  acid,  but  using 
no  i)ero\ide,  the  tailing  a.s.sayed  14  oz.,  and  the  concent  rate  7S0  oz. 
Evidently  the  acid  increased  the  grade  of  concentrate  and  also 
decreased  the  injurious  eirectsof  the  ferrous  sulphate  upon  extraction. 

Second:  efforts  were  made  to  precipitate  the  ferrous  and  copper 
sulphate.  A  test,  containing  these  sulphates  in  the  proportions 
indiciited    ill    the    analysis,    was    rendered    slightly    alkaline    bv    the 


LKKKCTs  OK  SOMHI.K  COM  I'ONKNTS  OK  o|(K  ON   KI.OTATION 


•2fi.1 


iulditinii  of  liiri,.  Iivilrale.  Tlie  tailing  assayed  12  oz.,  auii  the 
loiiicntratc  4')!)  oz.  Wlicii  .sDilium  liydrate  was  ust-il  in  place  of 
liiiif.  tiiu  tailin-;  a.ssavfd  ,s  oz.,  and  the  com-entrate  (300  oz.  With 
the  iron  preeipitatcd  hy  sodium  carhonatc,  the  tailing  assayed  6  oz., 
and  I  he  .-oncentrate  SOO  oz.  With  a  comliination  of  lime  hydrate 
and  sodium  earhonate,  Ihc  concnitrato  assayed  800  oz.,  and  the  tailing 
■  '•  oz.  Evidently  the  use  of  hydrates  and  earhonates  prodwees  nmch 
better  irsults  than  ean  he  secured  hy  acid.  The  eost  of  sodium 
hydrate  and  sodium  earhonate.  and  the  injurious  efTeets  of  the  latter 
upon  settling  and  filtration,  restricts  the  use  of  these  eheinieals. 
Lime  hydrate,  on  the  other  hand,  i»resents  a  cheap  and  efficient 
means  for  preventing  the  aci-umulation  of  ferrous  sulphate  in  ndll- 
s<dutioiis.  The  calcium  swlj>hate  resulting  from  the  reaction  is 
somewhat  defriinental  tn  flotation;  a  saturated  .solution  yielding  a 
Ifi  oz.  tailing  and  a  4r>()  z.  concentrate.  In  ordinary  practice  the 
solution  would  he  far  f r. m  saturated,  and  the  results  much  more 
satisfaetory. 

The  lime  hydrate  method  has  heen  successfully  used  on  this  ore 
III  roiitiiuious  mill-tests.  During  flotation  tin-  alkalinity  was  main- 
tained as  nearly  as  possible  at  0.02  Ih.  lime-oxide  i)er  ton  of  water. 
After  tlofafion,  half  the  circuit-water  was  wasted,  the  remaining 
half  heiufj  su])plemented  hy  fresh  water,  at  the  head  of  the 
mill;  lime  sulphate  thus  being  j)revented  from  accumulating  in  the 
.solution.  For  a  month  during  which  the  process  was  used,  the 
'•oncentrate  from  the  flotation  plant  averaged  HOO  oz.,  and  the  tailing 
ti  oz.  This  compares  favorably  wiih  a  20-oz.  tailing  from  gravity 
.oncenf  ration  and  a  12  oz.  tailing  from  flotation  in  an  acid  solution. 
Aside  from  eff"ecting  better  concentration,  tin'  lime  method  is  cheaper 
than  the  acid  process  and  is  not  injurious  to  subsequent  cyanidatioii. 

When  lim-  is  used  in  flotation,  extreme  care  must  be  exercised 
in  maintaining  the  proper  alkalinity.  The  table  submitted  herewith 
shows  that  the  best  restdt.s,  both  a.s  regards  extraction  and  grade 
of  concentrate,  are  seciirerl  when  the  alkalinity  during  flotation  is 
extremely  low  (between  O.Ol  and  0.02  lb.  CaO  per  ton  of  solution). 
Experiments  indicate  that  alkalinity  is  beneficial  to  flotation  but 
that  the  coagulating  effect  of  high  lime  ujion  slime  increas«>s  the 
affinity  of  the  slime  for  the  froth,  lowering  the  grade  of  concen- 
trate. When  the  coagulating  eff"ect  is  counteracted  by  the  addition 
of  sodium  carbonate,  or  wlien  sodium  hydrate  is  used  in  place  of 
lime,  an  alkalinity  equivalent  to  a  half-pound  of  CaO  per  ton  of 
solution    may   be    maintain d    without    harmful    efTccts   on    flotation. 


•Jtiti 


rilK    Kl.<i|ATI()N     I'lUICK: 


I'sually  a  hui-f  alkalinity  iiiaiiitaiiK'd  witli  iiuickliiuo  product's  etiiially 
t;o()<l  results. 

In  (irilcr  I'lirtliiT  to  study  tlic  ctTi'ds  <il'  ('(ipju'r  sulphate  on  flotation, 
a  solution  containing:  ti.dl',  CuSO,  was  cniployi'd  in  anotlur  sories 
oi  tests.  Wlien  this  solution  vas  used  alone  the  separation  \va^ 
e.\trei'irly  poor,  the  tailinj:  ass'iyini;  152  o/.  and  tiie  concentrate 
1(10  o/.  When  sutHcienl  quicklime  was  added  to  produce  a  slight 
alkaliiiiiy.  the  taiiintr  was  reduccil  to  24  oz.,  while  the  coucentrate 
increased  to  18(1  oz.  per  ton.  A  further  improvement  was  etVected 
liy  the  use  of  sodi.iUi  hydrate,  a  :!40  oz.  concentrate  and  an  11  oz. 
tailinir  hcinjj  secured.     This  was  still  far  from  sjitisfaetory. 

An  attempt  was  made  next  to  precipitate  the  copper  as  suli)hide. 
\>y  emitloyinj:  hydroi;en  sulphide  in  a  solution  renilcred  alkaline' 
hy  lime  hydrate,  a  tj  oz.  tailing  and  a  -i'tO  oz.  concentrate  were 
olitained.  Wlieii  sodium  sulphide  and  .sodium  hydrate  were  used. 
tlie  tailing-assay  was  reduced  to  3  oz..  and  the  oonecntrate  increased 
to  7(1(1  oz.  These  results  show  that  the  injurious  etTect  of  soluhle 
eoppcr  may  he  overci'iue  hy  the  use  of  hydrogen  or  sodium  sulphide 
ill  conjunction  with  lime  or  sodium  hydrate. 

The  foijiiwing  comdusioiis  were  estahlished  f(U'  the  ore  tested: 

1.  Sddium.  jiotassium.  and  ferric  sulphates  are  rather  lieneticial 
to  flotation  than  otherwise. 

2.  -Manganese  sulphate  has  jiractically  no  etl'ect  (  'i  tlotation. 

.'!.  Magnesium  and  caleium  sulphates  are  slightly  harmful,  while 
ferrous  and  cojiper  suli>liate  are  e.xlremely  harmful. 

4.  The  effect  of  magnesium  and  calcium  sulphates  may  lie  "vei-- 
eoiue  by  the  use  of  sodium  carhoiiatc  in  an  alkaline  solution. 

5.  The  effect  of  ferrous  sulphate  ■•an  be  owrcome  by  the  use  of 
sulphuric  aciii  or.  better  still,  by  enii)l.;y!ng  (luicklime.  caustic  soda, 
or  sodium   carbonate. 

ti.  The  effect  of  cnp|)er  sulphate  may  be  overcome  l)y  the  use 
of  hydrogen  sulphide  or  sodium  sulphide  in  an  alkaline  solution. 

7.  The  use  of  sodium  carbonate,  though  aiding  materially  in 
flotation,  is  of  doulitful  utility  in  plants  where  the  iialj)  must  be 
dewafered. 

H.  I.ime  liydrate  is  slightly  less  satisfactify  mefallurgically  than 
sodium  hydrate  or  sodium  carbonate,  but  the  us-  of  it  is  iiie.\j)ensivc 
and  aids  maferiallv  in  settling  and  filtering. 


Kl-or ATION" — A   I'ARAIX)X 


•2ti7 


FLOTATION— A  PARADOX 

By  Dl'DLK.Y  II.  NOKKIS 
(From  the  Miniiuj  and  Srit'iitific  Press  of  December  25,  1915) 

Flotation  is  a  paradox.  In  a  Howiiitr  iiiixtui»  of  tiiu'ly  pulvcriziMl 
ort'  ami  water  it  oaiisi'S  the  lieavy  metallie  sulphides  to  float  to  the 
surl'aee,  where  they  are  eoll,-  -ted  for  further  metallurgical  treatment, 
while  the  light  barren  ganjrue  sinks  to  tlie  bottom  and  is  run  into 
the  tailing-pond. 

Tills  api)arent  reversal  of  the  attraction  of  gravitation  is  due 
to  tiie  introduction  into  the  flowing  niixt\ire  of  a  snuill  quantity 
of  oil  or  other  emollient  in  such  a  manner  that  every  particle  of 
the  ore,  whether  metallic,  or  gangue.  is  brought  into  contact 
with  the  oil,  whereupon  there  is  what  seems  a  selective  actit)n  between 
the  oil  and  the  metallic  particles  sudi  that  these  becomi'  coated 
with  the  oil,  whereas  there  is  no  such  action  of  the  oil  upon  the 
gangue.  Under  proper  conditions,  at  or  about  the  same  time  tliat 
this  oil  coating  of  the  metallic  particles  takes  place,  tiiere  may  be 
caused  to  appear  in  the  flowing  mixture  bublilcs  of  air.  These  attach 
t.ieraselves  to  the  oil-coated  metallic  particles  and  stick  to  tlu'm  with 
more  or  less  tenacity,  making  a  new  entity  consisting  of  metallic 
particle,  oil-coating,  and  air-bubnU  .  The  specific  gravity  of  this  entity 
is  less  than  that  of  the  water  of  the  flowing  mixture;  thercui)on. 
because  of  the  attraction  of  gravitation,  and  not  in  spite  of  it,  the 
heavy  metallic  sulphides  float  to  ihe  sur'^'-'e  and  the  comparatively 
light  ga;ignc  sinks  to  the  bottom,  neither  oil  nor  bubbles  having  any 
tendency  to  attach  themselvis  to  the  barren  gangue. 

My  interest  in  flotation  arose  from  the  aceumulatiiui  at  m-  mine. 
the  Magistral,  at  Zaeatecas,  Mexico,  of  a  couple  of  hundred  tlioiisan<l 
tons  of  ehalcoi)yrile  ore  of  low  grade  which  I  had  tried  unsuccessfully 
to  treat  by  water  concentration.  I  came  to  San  Francisco  in  Feliruary 
100")  and  went  to  London  in  June  1P06,  to  investigate  the  two 
Hlmore  processes.  I  sent  some  of  my  ore  to  Ijondon  and  the  tests 
showed  a  saving  of  90%  or  more  by  the  vacuum  process.  I  set  up 
an  Elmore  lalwratory  plant  at  the  Magistral  mine.  9()00  ft.  above 
sea-level,  but  got  no  satisfactory  results — I  .judged  that  the  altitude 
acted  as  a  partial  vacuum  and  that  there  was  no  air  left  in  solution 
in  the  water.  T  then  led  a  small  pipe  from  the  air-compressor  and. 
t.  inp  a  folded  poeket-handkerehief  over  il  e  end  of  the  pipe,  fed 
compressed  air  into  the  flowing  mixture  througli   Ifi  thicknesses  of 


JtiS 


Till;    I'l.OTATIilN     I'KOCKSS 


till."  liiifii,  ]j()  lliivads  to  tlic  iiu-li.  I  fniiiul  lliat  with  a  li-rlit 
lncsKurc  of  ail'  the  l)iilii)ii's  coaleweil  on  coiiiiii>;  tliroii^ii  the  lahrir 
and  when  released  and  started  on  tlirjr  npward  jonrncy  were  of  a 
nniforiu  size,  about  tliat  ol'  a  niarrow-lat  pea.  Witli  y;riater  i)ressure 
the  si/e  of  tiie  huhhles  was  reduced,  but  tiie  action  of  the  air  was 
so  violent  that  the  mixture  was  like  a  boilinsr  geyser  and  everythini;, 
ore  and  ganf^ue  alike,  was  hronght  to  the  surfaee.  Thereafter  my 
flotation  experiments  were  suspended  until  one  day  in  a  Pullman  ear 
i>n  tile  Mexiean  Central  railroad  I  drew  some  wafer  into  the  hand 
wash-basin  and  I  noticed  that  it  was  as  white  as  milk,  but  presently 
became  just  ordinary  transparent  water.  1  saw  at  one  that  this  was 
due  to  an  artitieial  aeration  of  the  water  in  the  tank  under  the  ear. 
and  when  the  train  stoj)pe<l,  I  read  from  tiie  gauge  that  the  pressure 
in  till-  tank  was  11  atmospheres.  That  seemed  to  be  a  solution  of 
tlk'  problem  of  the  lack  of  air  in  the  water  of  the  Elmore  process; 
.so  1  i)atcnted  the  method,  together  witli  the  apparatus  for  utili/ing 
the  same. 

It  is  not  i)ropo.sed  here  to  discu.ss  any  theories  of  flotation,  surface 
tension,  ions  or  static  or  electric  conditions  or  to  ex[)lain  phenomena, 
of  which  we  at  least  know  a  little,  in  terms  of  sometiiing  of  which 
we  know  less.  Instead  of  tliat,  a  cla:-«itication  is  suggested,  homely 
and  commonplace  in  its  terms,  but  which  will  :mi)n'ss  upon  anyone 
the  exact  limitations  of  each  kind  of  flotation. 

The  oldest  flotation  is  that  including  Everson,  Fronicnt.  and 
others,  and  the  Minerals  Separr  ion.  It  produces  an  "agitation  to 
form  a  froth"  and  is  exactly  duplicated  by  the  activity  of  the  cook 
with  a  Dover  egg-beater  stirring  what  .she  is  apt  to  call  an  '"egg- 
omelette." 

Then  there  arc  the  Australian  processes  known  as  the  I)c  Havay 
and  the  Delprat.  where  an  acid  acts  upon  an  alkaline  carbonate  and 
releases  the  carbonic  acid  gas,  which  action  is  duplicated  in  common 
life  by  the  eflicient  Seidlitz  powder. 

Then  there  is  the  Elm(U-e.  which  gets  fmm  ordinary  water  the 
air  that  tlie  goldflsh  in  the  afiuarium  gets,  and  no  more. 

Tiien  there  are  the  Callow  and  the  Towne  processes,  where  air 
is  forced  through  a  porous  medium,  as  above  described ;  and,  finally. 
t!ie  Norris  process,  which  utilizes  the  air  dissolved  in  water  under 
I)ressurc,  f'.s  seen  in  the  Pullman  car  or  in  the  water-service  at  many 
])laces  on  th(>  eastern  shore  of  San  Francisco  Bay. 

I  believed  that  T  had  discovered  a  basic  principle  in  flotation, 
ami   in   September  190fi  I  applied   for  V.  S.  patents  on  the  method 


KLOTAT'DN  —  A   I'  VU  \IM)X 


26!t 


ami  nil  the  apparatus  For  usiiip  tlu'  Pullman  hiitiMi'S  in  Hotatioii ; 
later  I  took  out  patents  in  ten  foreign  countries  on  the  same  i)asis. 
Continuing  my  nietallursieal  investigation  in  the  summer  of  l'K)7, 
I  went  to  nearly  all  tiie  principal  eopper-eoneentrating  mills  in 
Coloratlo,  I'tah,  and  Arizona,  and  to  Caiianea.  I  saw  all  the  stars 
of  the  first  magnitude  in  the  copper  metallurgical  firmament,  hut 
they  shed  no  light  on  flotation.  In  tact,  I  was  asked  how  the  word 
was  s])elled.  The  not  result  was  that  I  went  hack  to  Zacatecas  and 
later  liuilt  the  Magistral  smelter.* 

About  this  time  I  received  word  from  my  patent  attorneys  that  1 
was  opposed  in  the  London  patent-otfice  hy  the  Minerals  Separation; 
but  I  instnicted  them  not  to  appear  and  the  case  went  on  without 
me,  as  will  be  seen  by  the  decision  in  the  case  where  it  is  cited  that 
"At  the  hearing  Mr.  Hallantyne  ai)pcared  for  the  opponents;  the 
applicant  was  not  represented."  Notwitlistanding  the  fact  that  the 
opposition  had  things  all  their  own  way,  ihe  London  patent-otfice 
over-ruled  the  o|)position  and  decided  in  favor  of  issuing  ni'  patent, 
and  .vhen  the  Minerals  Separati(ui  appealed  to  tlie  law-ol^icer  *he 
decision  wa.s  affirmed,  on  February  24,  1010,  and  tne  British  patent 
duly  issued  to  nic. 

In  the  recent  case  of  Minerals  Separation  against  .Miami,  counsel 
for  plaintiff  .said  tl'at  the  defendant  interpreted  the  older  patents, 
not  in  the  light  of  the  siate  of  the  art  at  the  time  the  respective 
patent  was  applied  for,  but  in  the  light  of  later  development.s.  It 
so  happens  that  a  reference  to  the  decision  in  Minerals  Separation 
V.  Norris  before  the  Hritish  patei  '  authorities,  shows  that  the 
Minerals  Separation  is  now  doing  that  very  thing. 

My  Hritish  ai)i)lication  was  dated  June  27,  lltOT,  and  was  opposed 
by  flic  Minerals  Scjiaration  on  the  grounds  of  prior  Hritish  |>a1en1s. 
as  follows: 

No.  12T7ti  A.l).   1905— Froment 

No.  20,2S:{  U»04— Elmore 

No.     7.S0:{  1" '.") — Sulman 

No.  2B.712  I'.kC) — Sulman 

No.  l:?,268  lf»07— Hoover 

These  include  the  liritish  ])atents  corresponding  to  some  of  the 
American  patents  on  tlie  basis  of  which  the  Miner.als  Separation 
sued  Tlyde  and  Miami  in  the  United  Stat.'s  courts,  and  the  suits  are 
now  pending.  The  case  in  the  Brit^h  pjUentotfice  was  d 'cided.  ;ind 


•See  'The  Copper  Handbook,'  ini2,  page  545, 


270 


TIIK    H.()T\'nnN    l'l(iH'h> 


till'  (iccisidii  lifiirs  (iaic.  .Miiich  I."),  lIKIil,  ( 'iiiisc(|iiriiil.v  llii'  [xisilidii 
of  till'  .Miiictjils  .Si'()!iriiti()ii  as  to  the  hasis  ol'  their  patnu  ri^'lits  as 
stali'.l  in  the  casi-  a^'iiiiist  iiic  li.twtfii  .(uiic  L*7.  l!M»7,  and  March  1,"), 
l!K):i,  is  the  trill'  statement  of  tlieir  own  idea  of  their  ri^iits  and 
l>(>siti(in  and  not  tiiat  wt  iij)  in  the  later  eases  some  years  after. 
and  in  the  liglit  of  tiie  more  mature  ('.\|)erienee  whieji  is  ])roteste(l 
\ty  .Minerals  Separation   itself  wiieii  used  liy  the  Miami  eompany. 

Here  is  the  Minerals  Sei)ai'alion  position  in  the  ease  against  Xorris, 
as  a|)|)eai-s  in  the  decision,  which  says  that  Mr.  Hallantyne  relied 
mainly  on  the  Sniman  and  Hoover  patents.  lie  contended  that  the 
nnderlyin'T  idea  of  the  various  ]>roce.sses  is  as.seried  in  Claim  No.  1 
of  tiip  Sulman  patent,  that  is.  introdiicinfr  hy  some  means  or  other 
air  under  pressure  into  |)uip  contaitiinj,'  oil  and  water  and  then 
allowing'  the  i)ulp  to  eonu'  into  a  vessel  which  is  open  at  the  top  to  the 
atmosphere. 

Claim  No.  1  o!'  the  .\merican  Sulman  jtatent  "consists  in  mixin<; 
the  powdered  ore  with  water,  adding  a  small  proportion  of  an  oily 
li(|uid  haviiiR  a  i)referential  affinity  f(U-  metalliferous  matter 
(amounting  to  a  fraction  of  1%  on  the  ore  >  agitating  the  mi.\ture 
until  the  oil-coated  mineral  nuitter  forms  into  a  froth  and  .separating 
the  froth  from  the  remainder  l)y  flotation."'  There  is  no  liiat  in 
Mr.  Ballantyne's  presentation  of  his  ca.se  before  the  London  patent- 
otllice  that  he  or  his  client,  the  Minerals  Separation,  placed  any 
importance  ui)on  the  little  plira.se  in  parenthesis  (amounting  to  a 
fraction  of  1','  on  the  (u-e)  and  it  can  hardly  he  imagined  that  any 
court  would  permit,  at  this  late  day.  a  siil)stitution  of  another  idea 
for  what  Mr.  Hallantyne  claimed,  in  tlie  ea.se  against  Norris.  to  he 
the  underlying  idea  of  the  various  processes. 

The  decision,  in  my  favor,  contained  these  words:  "It  a|M)ears 
to  me  theri'fore.  that  the  applicant  is  entitled  to  a  patent  for  his 
invention****!  decide  therefore  to  seal  a  patent  on  the  applica- 
tion***."  The  Minerals  Separation  ap))ealed.  but  the  decision  was 
.-inirmcd  and  the  patent  is.siied  February  24.  IHlfl.  The  Federal 
Circuit  Co,\rt  of  Ap|>eals.  on  appeal,  decided  the  Ilyi'e  case  against 
the  Minerals  Separation,  in  tlies(>  words: 

"We  hold  that  to  sustain  tlie  appellee's  patent  would  be  to 
give  to  the  owners  thereof  a  monopoly  of  that  which  others  had 
discovered.  \Vhat  they  claim  to  lie  the  new  and  useful  feature  of 
their  invention.  ■  •  st  '  d  by  their  eon  ise!.  is  agitating  the  mixture 
to  cause  the  oily-coated  mineral  to  form  a  froth.  As  we  have  seen, 
that    feature  was  charly  anticipated  by  the  prior  art.  and  when  the 


FIX)TATInN- 


'AH  \l><).\ 


271 


elt'iiicnfs  of  till'  appellee's  elaiins  are  read  one  liy  one,  it  will  be 
fouiiil  that  each  step  in  their  proeess  is  fully  deserilied  in  iiion'  than 
one  (tf  the  patents  of  the  prior  art,  with  the  single  exception  of  the 
reduced  quantity  of  oil  which  they  use." 

The  .iud^nient  of  the  court  l)elow  wa.s  reversed  hy  the  Circuit 
Court  of  Appeals  and  a  motion  for  a  re-heariiig  was  defied.  Then 
the  Jlinerals  Separation  applied  to  the  U.  S.  Supreme  Court  for  a 
writ  of  certiorari,  which  was  {^ranted,  and  the  ease  is  now  hefore 
that  court.  The  Minerals  Separation  advertised  that  the  Su])reme 
Court  had  pranted  their  petition,  without  going  into  details  as  to 
just  what  the  petition  was.  As  a  matter  of  fact,  the  granting  of  a 
writ  of  certiorari  hy  the  Supreme  Court  is  in  no  sense  a  decision 
on  the  merits  of  the  case. 

Prior  to  1891  an  appeal  to  the  Supreme  Court  from  a  Circuit 
Court  was  a  matter  of  course,  if  tlie  sum  involved  reached  $1()()(), 
the  result  being  a  crowded  calendar,  years  behind.  In  1891  the 
Judiciary  Act  abolished  the  Circuit  Courts,  merging  their  functions 
in  the  District  (.'ourts,  and  creating  the  Circuit  (  oui-ts  of  Appeals 
with  final  jurisdiction  in  many  classes  of  eases,  including  patents. 
The  Act  provided  for  a  writ  of  certiorari  in  ea.ses  where  the  judg- 
ment of  the  Circuit  Court  of  Appeals  is  final  and  the  ndes  of  the 
SiiOreme  Court  say  that  the  writ  will  issue  where  ea.ses  of  great 
gra  'ity  or  importance  are  i?ivolved  or  where  two  different  Circuit 
(  on  'ts  of  Appeals  have  rendered  conflicting  decisions. 

The  proceedings  on  the  application  are  very  technical.  A  petition 
must  be  presented  setting  forth  the  facts,  of  the  case  together  with 
the  reasons  for  the  writ.  Two  weeks  notice,  or  west  of  the  Rocky 
Mountains,  tlirt^e  weeks,  to  the  adversary;  and  no  petition  will  be 
granted  within  a  fixed  time  before  the  end  of  the  term.  With  the 
petition  must  be  filed  a  certified  copy  of  the  papers  on  winch  the 
court  below  acted  and  30  copies  uncertified.  No  oral  argument  is 
allowed.  As  Chief  Justice  Fuller  expressed  it:  "The  inquiry  upon 
the  application  is  whether  the  matter  is  of  sufficient  importance  in 
itself  and  sufficiently  open  to  controversy  to  justify  the  writ." 

At  the  October  term  of  1914,  at  which  the  petition  for  the 
Minerals  Separation  writ  was  granted,  there  were  45  applications 
for  writs  of  certiorari,  of  which  11  were  granted  and  34  denied. 
In  the  reports  no  reason  is  given  for  the  Court's  action  in  deciding 
petition  for  certiorari;  but  it  is  extremely  probable  that  a  certain 
number  of  the  applications  were  denied  because  the  trclmical  require- 
ments of  the  rules  were  not  observed.     That  is  about  the  gist  of 


:V: 


-'-  TIIK    KI.OTATluN    I'UOCKSS 

tlif  i)rcsfiit  stale  of  the  lly.lc  I'iisc     TIiitt  has  Im'.^ii  no  ])ar(loii  nor 
coninuitation   nor  rcvci-siil.  lint   nuTcly  a  stay  of  .xfcnlion. 

Thf  MiniTHls  Separation  also  advertised  tliat  tliey  ha<l  M  patents 
oil  ttotation.  siiK^e.stinjr  that  thrir  coWeelion  inrhides  ahoiit  all  the 
flotation  i)atents  that  have  any  real  value.  I'nfortiinately  for  this 
view,  there  is  a  letter  in  existence  written  Ky  th.*'  .Minerals 
Separation   which  says:      'It    is  our  custom   to  add  flotation   patents 

to  our  collfctioii   if   they  can    I htained    reasnnalily   whctlicr  tlicv 

are  of  any  inuiH'diate  iiiiixirtani c  to  us  or  not."  That  heiiifj;  tlicir 
custom  and  the  decision  of  the  Circuif  Court  <>.  .\])pcals  lieintr  so 
stronuly  against  them,  tlic  inference  is  irresistihie  that  however  little 
these  waifs  and  strays  of  patents  were  houirht  for,  they  w.-re  not 
worth  it. 

One  lan  understand  the  keen  regret  on  the  part  of  tle^  .Minerals 

Separation    that   their    Froiuent    pi ess   had    not    heeii    patenteil    in 

this  .•ouiitry,  hut  only  in  Italy  and  KiiKland.  They  started  with 
the  Catterniole  ])roces.s.  which  was  not  a  succcs.s,  and  aci|uircd  the 
Froment  afterward.  The  Cattermole,  usiiif;  4  to  (>';  of  oil.  was 
an  iiii|u-((venit  on  the  KImore,  which  used  nuue.  They  accpiircd 
the  Froment.  which  was  a  bulilile  i)rocess  as  apainst  the  i>roci'ss.s 
usini;  only  oil.  and  then  lie<;an  a  new  series  of  American  applications 
for  patents.  The  attempts  of  the  Minerals  Separation  to  jrct  a 
foothold  in  this  country  for  their  process  of  flotation  hy  ■■a<;itation 
to  lorm  a  froth"  hetrin  with  >s:ir).12()  Siilman  <t  al.,  dated  .Vovcniher  (i, 
1!M)(),  This  contained  the  ajritation-to-form-a-froth  idea  Imt  it  is 
crudely  woi-ked  out.     Next  came: 

'.•."):s,746.  Hoover.  A|)ril  "),  liHO,  with  three  l.eaters  in  an  agitation- 
vessel  ;  but  this  claims  )nly  one  in  ])atent  for  apparatus.    Next  came 

'Xh).0]2.  Sulman.  April  12.  IDIO,  for  process  corresponding  to 
Hoover's  apparatus.     Then 

fi.K'i.Sf)?.  Tloovcr.  December  27.  1910.  claims  mixing-vessel,  an 
Imitator  therein,  sjiitzkasten ;  also,  a  secondary  mixing-vessel.     1  iien 

l,Ofi4.20f».  in.bbard,  dune  "in.  lOi:).  f'laim  1.  Apparatus  for 
ore  eonccntration  by  gas  flotation,  consisting  of  two  ad.jaeeut  mixing- 
vessels  each  containing  a  rotating  agitator  and  a  sjtitzka.sten  con- 
tiguous.   (  laims  :i,  4,  and  o  cover  a  number  of  these  elements. 

l.(i(i7.4S.").  Nutter  if  al,  July  15.  lOl.'i.  I'rocc.s;  f,,r  concentrating 
ores  consisting  of  agitating  water  containing  mine  al-frothing  agent, 
r-moving  the  froth,  agitating  jiulp  again  with  addition  of  anothiT 
agent,  producing  anothi  r  froth,  "and  so  o:i." 

1.0,si4.1fl(;.     I'.roadbridge  it  nl..  January  1.!.  lf)14.     Apparatus  for 


Kl.oTATlON  —  A   I'  \H  MHIX 


'.T.i 


agitfitidn-t'rotliiiit^  process  coinprisiiit,'  ii  sfrics  of  iiKitatiiif,'  and  aerating 

\esjsel.s  an<!   il  series  of  s()il/kastens. 

1,1U1,50<J.  Uradlonl,  June  2:{,  Htl4.  Introduces  tlowin^r  mixture 
In. in  mixer  into  a  eentriluKai  pump,  adding'  siilplmrie  acid  and  air 
and  steam.     Ajfitates  to  form  a  froth. 

In  all  these  patents  the  Minerals  Separation  i.s  the  assi^rnee  and 
the  gradual  advance  is  noticeahle  from  the  first  idaim  of  one  ve.s.sel 
to  the  next  claim  for  two  mixinjr-vessels,  then  one  agitation  and 
another,  "and  .so  on."  How  far  on  is  "so  on"?  Do  they  claim  to 
use  a  third  ami  a  fonrtii  ve.ss<d,  ami  if  so.  must  they  use  a  ditTerent 
"mineral  froth-ntr  ap'iit"  every  time,  or  can  they  repeat  with  the 
same  one?  l\y  the  way.  just  what,  in  a  strictly  legal  sense,  is  a 
"mineral  frothing  agent"?     Does  this  cover  any   further  dis.'overy 

of  such  an  a^'ent  that  is  tli.is  preempted  in  advai .'     Is  it  anytiiing 

and  everything  that  will  make  a  froth  with  a  mineral? 

•Much  of  the  phraseology  of  the  Minerals  Separation  |)atents  is 
vague  and  loose-jointed.  If  intentiotndly  so.  with  the  idea  of  making 
the  most  favorahle  interpretatio!i  in  any  circumstances  that  may  he 
pres(Mited.  the  oh.ject  is  self-defeated,  for  it  is  an  elementary  principle 
of  legal  interpretation  that  words  shall  he  strictly  interpreted  against 
the  person  using  them. 

This  ti'iidency  is  shown  in  Mr.  Hallantyue's  statement  that  Claim 
No.  1  of  the  Sulman  ])atent  is  for  the  underlying  idea  of  tiie  various 
|)rocesscs.  introducing  liy  some  means  or  other  air  under  pressure 
into  pulp  containing  oil  and  water.  "By  .some  means  or  other," 
by  anv  pos,siliie  means,  and  Minerals  Separation  claims  them  all. 
"Agitati'ii  to  form  a  froth"  was  their  great  (daim.  and  in  practice 
they  .seem  to  claim  any  agitation  for  any  purpose  whatever  and 
any  froth,  however  formed.  So  far  has  this  heen  carried  that  it  is 
said  that  Callow  has  desisted  from  the  use  of  a  paddle  to  keep  his 
canvas  clear  from  sand,  although  disclaiming  any  intent  of  forming 
a  froth  with  it,  tiecaus<'  the  Minerals  Separation  company  takes  the 
paddle  to  form  a  froth  and  pmpnses  to  keep  it  for  all  otiier  pur- 
poses. 

Th"  i)resent  .situation  of  flotation  metallurgy  is  intolerahle. 
There  is  every  appearance  that  some  time,  perhaps  year's,  may  pass 
without  a  tinal  .judgment  of  all  the  Minerals  Sejaration  litigation 
and  meanwhile  they  keep  on  collecting  royalties  from  parts  of  the 
mining  industry  that  are  availahle  for  coercing  the  rest.  Progress 
is  halted.  Development  is  retarded.  Can  nothing  he  done  to  nd 
the  metallurgical  Sinbad  from  this  Old  Man  of  the  Sea  ?    Statements 


274 


TIIK    H,(»l\Tln.s    I'HiKKSS 


liix-  livHy  iiia.l.-  that  in  case  of  a  lii.al  Miti.Tals  ScparatioM  victory 
a  stn.l  accountal.ilily  uiil  !„■  iv.iuiiv,!  Iruin  all  mfnnu'.rs. 

The  Nonis  |.n...,.ss  Iuin  f,'iv.ii  .•xccncnt  nsiilt.s  with  the  ai)paiatu.s 
of  iM.th  MiiirralH  Separation  ai.,1  of  (■all.)w.  the  .■om.-ci.i  rate  Immii; 
of  .NrcllcMt  urad-  from  the  roiijfh.r  and  from  a  sl,.«,.r  stirrinjr- 
ai.i'aratiisuftcr  the  Klnior..  St  vl..(,f  mixer.  The  proeevs  ran  he  adapted 
to  anv  tvp..  of  tank,  hox.  spit/kasten,  .,r  other  re.epia.je  and  there 
IS  no  danirer  ,.f  .lefeat  from  an  atta.'k  on  tiie  Norris  patents  hv  the 
Minerals  Separation.  A  method  ran  he  .levised  to  float  ores  uiih.mt 
^lsln^'  the  .Minerals  Separation  |mt,.nts  or  paying'  tiiem  royalties 
J  lie  day  ol  royalties  .m  ,laily  tuiuuiire  ,s  past.  Anan-emeiils  ean 
he  made  lreein>r  llie  induslry  from  this  toll  and  also  from  extravajrant 
prices  for  |patented  machuiery. 

Tlie  sii-}r,,s,i„„  |,;,s  recently  hec,  made  that  one  of  the  most 
Heeled  thinjrs  in  the  mineral  industry  at  the  pn^s^Mit  tim..  is  .s.mie 
easy  way  of  makinsr  flotation  tests  at  the  mine;  so  that  a  mill. foreman 
">•  Miine-l,oss  may  he  ai,h.  to  make  his  tests  on  his  ores  and  .lecde 
whether  or  not  they  are  su.sceptihlc  to  flotation  an.l  then  .hsit;!. 
a  l-nn.e.ss  for  I  real  in-  ihcm.  Of  ,.o,irse,  any  a.vom|.lisliments  llmt 
a  Inreman  .,r  min,.  I,n.s,s  may  have,  add  to  his  value:  and  ahility  to 
s't  a  hrokeii  let;  or  cure  a  ease  ,,f  mountain  f,.ver  mitrlit  earn  for 
hirn  an  additional  salary,  hut  ashle  from  lii-sf  aid'  to  the  iniured 
no  one    would    want   to   put    him.s..lf   in   the   hands  „f  tlu-    foreman' 

or  the  und.rsrroniid  min,.d,oss  for  medical  treat nt.     It  is  the  .sain.' 

way  with  tests  on  flotation.  Aside  from  mere  preliminary  experi- 
nu'iits,  testiiiff  oivs  for  flotation  is  as  miK'li  a  separately  protVssional 
iMatter  ,is  eanntr  for  a  t.rokeii  leg  "r  a  ease  of  mountain  fever 
.MetallllI•^'ical  ennineorinp  is  now  so  far  advanced  that  tli.'rc  is  hut 
small  rea.son  for  goiuf?  astray  in  the  matter  of  treatment  of  ores 
hy  t|..t,iii,,ii,  provid,.,!  ade(piate  preliminary  tests  are  made  hv  expert 
nh'tallurtrical  entrineers.  The  cost  of  .such  tests  is  triHin-  and  their 
importance  and  value  not  to  he  exa^'f,'erated. 

One  threat  rea.son  why  a  mere  practical  niillman  or  miner  cannot 
devise  a  process  from  the  patent  claims  and  specilications  is  that 
mo.st  of  the  imi)ortant  cleinent.s  of  the  actual  installati.m  are  omitted 
from  the  j.atent.  The  e.s.sential  principle  of  the  patent  of  Klijus  Howe 
for  the  sewiii}?  ma.'hine  wa.s  that  the  eye  was  in  the  point  of  the 
needle.  Taking  that  for  a  starter,  how  far  would  a  iium  get  toward 
huilding  a  modern  Singer  from  the  Ilowe  patent?  It  is  like  an 
e.iuation  in  calculus.  Take  such  an  equation  representing  a 
mechanical  movement  ami  com])are  it  with  another  equation  of  the 


:^7^»irl3C/St, 


KT,OT\Tln\  —  \    I'VKMMiX 


path  n(  !,  ...Hii.'t.     l)iir.T,.|itial..  both  ;,M.l  „ul  >fo  tl iisiaiil   laiiMPs 

ami  III,,  ilitr.ivritial  .Miiialioiis  ini^'ht  hr  i,|..iili,al  iii  Ion,,  Ur  int,.^rat,. 
lli.iM.  I)u  y,.u  K'-'t  l)a,.k  y.Mir  iiKMhatiK^al  iii,.v,ii„.|it  an,!  y,,iir  r„i,wl\ 
orliit  .'  V,iu  ,1,,  iMil.  Viiiir  iDiistaiit  lailiirs  ,1,.  nol  iv  appear.  TIh' 
sjirnc  way  wilii  palnit  sp.vitirali.iiis  aixl  clainin.  Tlwy  c.Mtaiii  only 
""'  'lifffi-i'iitials.  Ill  ia.t,  a  i.-.>.nl  I.-II.t  iVoni  the  I'at.Mil-l  )lli,"c 
sJiiil:  --It  IS  .sii^'Ki.st,.,!  that  tli.^  .iaiiiis  •■liiiiiiiat,.  all  iiiiiu.c,..s.sarv 
ivIVrciiiMs  t,i  slniclun'  ami  thai  llu^y  Ur  liiiiit.M  i..  ih.^  a.^tiial  pnu-.^ss 

St, •[IS.  " 

Hy  a  pr.ip.r  coiiihinatinii  ,if  iiihivsls,  ii,,t  ,,ii|y  ,.aii  tlnrc  tu- 
av„i,l,.,|  tj„.  |,ayi,i,.|it  ,.1'  n.yalli.s  ,.i,  „ivs  trvahd  an, I  hi^rli  ])ri,-..s 
I'-ir  pal,.|il,,l  iiiacliiiicry :  an, I  ii„t  only  ••aii  ,v,Ty  iiiill-,,\Mi,.r  he 
asMiri',!  of  th,.  .•oiislant  liitfli  cnicu.n.-y  ,.f  his  plant,  hut  h.^  ,.a,i  1,,. 
protc'tcl  H^fainst  intViiiKiiiK'  pah^nts,  an, I  if  sii,,l  f„r  iiirriiiu,.|n.nt 
he   I'an    Im.   ,1,  r,ii,l,.,|    at    a    tiiHintr   cist    t„   liiiii.s,.|f.    a    ".ninral    fund 

lieinn  pi-(,viil,,l.  al  a  .small  pctvcntai.','  ,,1"  what  tli-^  ns '  ihc  .MiiuTals 

Scparaliiin  i)al,.|il  w,.iil,|  .usi  him  'rj,,.  way  t,,  ,|„  is  t,.  pcrlVct  a 
pnicfss  in  a  imtallurs.'i,-al  lali,.rat,,ry  to  tit  th,.  sp,,-ial  iifc  in  ca,'!! 
ease.  Wli,.n  ih,'  pnic'ss  is  p,Tf,Mi,,l  cart'  must  ho  takfii  that  it 
iiiclu(l,.s  til,,  pat, Mil  pi-in,-ip|,.  uiKhr  wlii,.|i  it  is  t„  h,.  Ii,-,.nsi.,l  and 
docs  nol  iiifiiiif:,.  any  .itli.T  jiatfiit.  In  on,.  iiiin,>  in  th,.  Xintli 
('mint    uhcrc  a   li,)m,.  nunli.  |)fo,-(.:s  has  hci.ti   pali-h,.,!   uj),   it  sc.ms 

as  thoiitih  cvi.ry  wvll  kii,,uii  Holatioii  pat.'tit  has  1 n  infniif;,.,l.  and 

yi'l  th,.  proc'.ss  will  n,it  work  as  it  ouKlit. 

Wt.JI.  siijipos,.  th,.  pr»<rr-aiii  is  carrifd  out  ami  th,.  .\,.iTis  i)ro,Tss 
is  niMiiTally  adopt,.,!,  and  the  Ify.!,.  aii.l  Miami  suits  aiv  ,l,.,.i,|..,l 
in  fav,)r  of  the  Minerals  S,.paration.  That  lias  no  ,.tr,.<.t  on  the 
Norris  jirocess.  not  hcinp  a  party  to  the  pro.scnt  suits.  A  m-w  suit 
would  liavc  to  he  hroiipht  a^aiiLst  n<'w  delVmlants  and  another  term 
of  yt.ars  pas.s(.,l  l(ef,)r,.  the  Minerals  Separation  eould  hope  to  p't 
any  moii<.y.  how<'v,.r  fav,)ral>le  their  ease.  l{ut  tii,.ir  eaw  would  not 
be  favorable.  The  first  thinp  that  th.-y  would  meet  woidd  |„>  a 
certified  copy  of  th(.  proeoedings  in  their  own  eountry  wiiere  tlieir 
own  (Jovc.riiment  decided  that  the  N,)riis  process,  irithounh  the 
appli(.aiit  was  not  rcpreseiite.l  at  the  hearing,  was  not  an  infringe- 
ment of  the  five  patents  governing  the  Fromeiit.  the  KImore.  or  the 
Minerals  Separation  processes  res|)ectiv,.|y. 

The  Jlinerals  Separation  people  were  so  sure  of  their  strat,.gic 
position,  so  confident  that  their  American  patents  would  o,.  sustaiired 
by  the  c,)urts  that,  from  what  sc,.ms  mere  want,inn,.ss,  conditions  were 
imposed   upon   the   licensees   that   were   intolerabl,. ;    with   the   result 


'■-•I 


=  V  .i  ..-r'  .  '*■.-< 


%^.^ 


'^r^^^ 


-1.'^,  r^i'-*.^' 


MICROCOPY    RESOLUTION    TEST    CHART 

ANSI  ot^d  ISO  lESI   CHART  No     2 


1.0 


I.I 


1^  1^ 

I:  y£ 


112.5 
2.2 

20 
ill  1.8 


1:25    III  1.4     mil  1.6 


^Fl  't--'-    t.ji;'    Mi;i-      -i-ee- 

' '16}    *82  -  0300  -  Phone 

^S  "fiJ  288  -  5989  -  Fa» 


276 


Tin:    .'I.OTATION    I'liOC'KSS 


of  ,1  concerted  movement  on  tlif  part  of  the  whole  niiniii<r  iti,lu.str.v 
to  defeat  the  .Alinerals  Separation  patents  and.  from  the  j. resent 
outlook,  with  every  prospect  of  suceess. 


FLOTATION  OF   GOLD   ORES 

(From  the  Mining  and  .Scientific  Press  of  December  23,  I'Ji.j) 
The  Editor: 

Sir— Mr.  A.  E.  Drueker.  will  known  for  liis  work  in  eyanidation, 
in  a  letter  appearing  in  your  is.sue  of  Novemlier  20.  maile  .some  verv' 
pertinent  remarks  in  regard  to  flotation,  more  partieularly  eoneei^inng 
its  applieation  to  gold  and  silver  ores.  His  view  is  that  of  a  metal- 
lurgist rather  than  of  the  nmn  interested  in  the  introduction  of 
flotation.  There  is.  as  .Mr.  Drueker  pc.inis  out.  a  i)laee  in  lU'arly 
every  gold  and  silver  mill  for  a  flotation  plant,  and  from  the  work 
that  I  have  dmie  .so  far.  I  have  eome  to  the  .same  .onelusion. 
namely,  that  flotation  will  he  n.sed  in  eoniieetion  with  water  eon,'en- 
tration.  and  that  its  hest  place  in  a  cold  and  silver  mill  is  in  the 
treatmenv  of  the  slime. 

I  think  that  in  the  futtire  a  common  im-thod  for  the  treatment 
of  gold  and  silver  ores  will  he  concentration  hy  water  and  the  treat- 
ment of  the  resulting  sand  hy  cyanide,  with  the  use  of  flotation  for 
the  slime.  A  scheme  like  this  could  he  adopted  in  many  cases,  thus 
ohviating  the  neoes.sity  for  fine  grinding.  The  removal  of  tiie  pvrite 
from  the  sand  woid<l  allow  quick  treatment  hy  eyanidation  of  the 
sand  and  the  flotation  of  the  slime,  which  would  do  away  with  the 
most  ".xpeiisive  part  of  the  cyaidile  i)lant.  natnely.  the  slime  annex. 
However,  the  constantly  recurring  (piestion  would  he:  what  to  do 
with  the  flotation  emicentrate.  ( 'onsid-M-ahle  w(H'k  is  iwv  heiiig 
done  in  our  lahoratory  to  ohtain  a  flotation  concentrate  low  in 
insoluhles.  The  average  amount  of  insolidiles  is  ahout  .lO';.  I  am 
now  carrying  mit  some  tests  to  reduce  these  in.solnhles  to  a  mini:iium. 
hecause  if  the  concentrate  is  to  he  handled  or  shi|.pe.l.  it  shoid.i 
contain  the  lowest  possihle-  perc  ntage  of  insoluhc's.  Flotation  is 
now  on  the  maj)  and  will  he  appearing  constantly  in  the  flowsheets 
of  tli(>  future. 

ClIAS.    RfTTKIiS. 

San  Franci.sco.  Decemher  1:{. 


TESTING  ORES   FOR  THE   KI.oTATKl.V    I'lJOCESS 


277 


TESTING   ORES   FOR   THE   FLOTATION   PROCESS 

By  0.  C.  Ralston  and  Glexx  L.  Ai.lex 
(From  the  Mining  and  Scienlific  Press  of  January  1,  1916) 
lNTH0DicTi,,N.  *Altli-ugl,  tile  suhjrrt  of  testin-  l\.r  Hotatiou 
lias  hwi,  wdl  presfiite,!  in  T.  J.  Iloovei-'s  hook  on  ■Con.-cnfrating 
Ores  by  Flotation,'  there  is  need  of  later  infon.iation  on  tiiis  timely 
subjeet.  Mueh  testing  has  been  done  in  laborat:  ries  not  eonneeted 
m  any  way  with  the  Minerals  Separation  eonipa-iy.  with  whch 
Mr.  Iloovvr  was  formerly  iiss<u'iated  as  nietalliirfjieal  enfjineer,  anil 
there  have  been  developed  methods  of  investigation  that  may  j)rove 
suggestive  to  many  experimenters. 

On  that  aceount  we  have  eompiled  data  on  the  subject  of  testing 
both  from  the  literature  available  and  from  our  own  e.xpcrienee, 
as  well  as  from  what  we  have  seen  in  other  laboratories.  This  paper 
is  de.signed  to  present  the  results  of  this  eompilation.  with  a  eritieal 
Ji.seussion  of  the  more  important  methods  now  in  vogue. 

On  aeeount  of  the  empirical  state  of  tiie  art  of  flotation  a  great 
deal  of  testing  is  neeessiiry  before  large-scale  practice  can  be 
commenced  on  any  ore;  therefore  a  small  laboratory-machine  is 
iieccs.sary  in  which  many  t.'.sts  involving  many  variables  can  be  made 
m  a  short  time.  The  iiuichine  must  be  so  designed  and  so  operated 
that  a  close  approximation  to  the  results  possible  with  full-sized 
tiotatiou  machinery  will  be  obtained.  In  a  mill-i)lant  it  is  a  matter 
of  some  (litiiiculty  to  control  conditions  through  a  wide  range  of 
such  variables  as  temperature,  acidity,  quantity  of  oil,  i)crcentage 
of  solids  in  pulp,  fineness  of  grinding,  etc.,  and  as  the  proper  treat- 
ment of  a  given  ore  can  lie  a.seertained  only  thi-ough  testing  it  first, 
a  critique  of  the  testing  methods  in  use  is  in  order. 

Many  people  have  had  the  experience  of  reading  the  available 
literature  on  flotation-testing  ami  of  failing  to  get  .satisfactory 
results  when  the  described  testing  was  attempted.  To  actuallv 
witness  some  goo.l  t.'st-work  an<l  learn  thereby  the  appearance  of 
froth,  the  .'xact  manii)ulati(pn  of  th.>  machine  and  froth,  goes  far 
toward  bringing  I  he  beginner  to  a  p(,int  where  he  can  test  efliciently. 

•By  iierniission  of  the  Director,  IT.  S  Hnreau  of  Mines.  Comn'unicated 
by  I).  A.  Lyon,  metallurRist  in  charge  of  the  Salt  Lalie  station  of  tl.o  v  s 
uureuj  of  Alines,  co-oppratinR  with  the  University  of  Utah.  O  C  Ralston 
Assistant  .Metallur-iat  of  U.  S.  Bureau  of  Mines,  and  Glen  L.  Allen,  Research 
Fellow  of  the  University  of  Utah. 


278 


TIIK    KI.UT  \'ri(lN     I'HilCKSS 


X( 


<\'   tin 


lit 


enituii'   iiicntiiins 


tlic   n 


tlijit    it    is  (lilliiMill    t(i   fift 


a    lii^'li    pcmMitafrc    of    extract  ion    and    a    lii<;li    frradc    i)t'    Hotati 


(iiK-fiiti'atc    at    tlic    same    linn 


•Ii(>    1 


botil    of   tlii'sc   tl 


ic^rimicr   (it'tcii    strives   after 


i!ni.'s   in   a  siii^He  test,   uiiereas  lie  slicnilil   deteri 


aeli   eaii   he  atti'iiied   betore   he  attempts   to  (ihtaiii   hoti 


taiiodusly.     Fiirth 
to  give  as  trond  result 


)re,  it  is  (litHeult  t 


s  as  a  larjre  one.  i 


So   the  small    maeli 


o  iiiani|)iilate  a  small  iiuieliiiie 
inti:  aftei'  eonsi(|ei-ahle  i)raetice. 


me    is   jrenerall.v    pes,simislie.    eom|iared    with    tli 


larfjie  one.     It   is  jiraetieally  essential  for  the  bej^iimer 


lo  \veij;li  and 


Feed 


Concentrate 


Tailinof- 


Flu.    54.       TUK    M.Mgl  ISTKN    Tl 


a,s,say  all  of  his  iirodiicts  in  order  to  .see  if  the  e.xtraetion  and  the 
grade  of  eoneentrate  are  satisfactory,  where  an  experienced  manipu- 
lator can  often  tell  t>y  aid  <if  past  experience  and  the  use  of  a  f,'la.s.s 
or  microsi'ope  whether  he   is  getlinir  good  results  or  not. 

With  tlie.se  points  in  view,  we  shall  deserihe  first  th.  satisfactory 
machines  and  their  ojieration.  Then  we  shall  give  a  more  general 
cNpositioii  on  what  variables  to  study  and  what   points  to  observe. 

I'Motation  ter,f  apparatus  must  necessarily  I)e  ela.ssitied  in  the  same 
way  as  large-scale  machines,  naiiiely.  as  (iliu-flotafion  machines,  acid- 
tiotalion  macjiincs.  and  t  rotli-maeliines  of  b(^tli  pneumatic  and 
niechanically   agitated    types.      Film  flotation,    as   exciiiplilied   in    the 


TKSTIMi    UHKS   I'dU    rill:    FI.l  ITATK  l.N    I'liOCKSS 


L'Tft 


.Mai-(iuist.-ii'  ami  in  tlir  Wixxl  ina.'liincs.  ilocs  not  s.tiii  to  have 
tlic  satiif  \vi(k'  applica'ioii  as  docs  I'roth-Hotatioii ;  liciic.'  little  need 
liu  Siiid  jiliout  tliciii. 

Film-Flotation.  .Marciuisten  tiilics  have  smiIi  siaail  capariiy  that 
a  siiisrk.  tube  is  small  enough  for  tcst-.vork  n  a  few  pounds  of  ore 
at  a  time  (see  Fig.  54).  A  small  4-ft.  tube  is  known  to  give  trust- 
woi-th.v  results,  although  a  longer  oiu'  is  more  desiiable.  Testing 
with  a  ]Ma<(]uisten  tube  was  done  for  several  years  in  the  laboratory 
of  the  (leneral  Engineering  Co.,  of  Salt  Lake  City,  of  whieh  eoiii])anv- 
■L  M.  Callow  is  i)resideiit.  Sinee  Mr.  Callow  has  begun  tlie  e.\i)loita- 
tion  of  his  own  pneuiiiatie  frothing-ma.'hine  this  work  has  b.>en  set 
aside. 

The  Wood  niaehine  can  be  built  in  miniature  and  for  several 
years  a  small  niaehine  of  the  type  sketched  has  been  used  in  the 
plant  of  the  Wood  ore-testing  works  at  Denver.^  This  small  maeliine 
was  about  two  feet  long  and  one  foot  wide.  The  method  of  operation 
is  the  same  as  that  of  the  full-si;;ed  machine.     (See  P'ig.  5').) 

As  neither  of  these  niaehines  has  been  inueh  used  in  practice, 
they  are  merely  mentioned  'or  the  sake  of  completeness.  Hoover'' 
lias  recommended  a  test  on  a  vaniiing-plaque,  so  that  tin'  sulphides 
will  float  ort*  onto  the  surface  of  the  water,  but  we  consider  this 
test  of  practically  no  value.  Hoover,  however,  acknowledges  that 
it  is  merely  a  test  illustrative  of  the  film  processes. 

In  testing  ores  for  the  Potter  or  the  Delprat  processes.  Hoover's 
text  is  again  the  source  of  infonnation.  An  illustrative  test-tube 
experiment  is  pictured  in  Fig.  56.  Tubes  containing  3%  ILSO,  or  acid 
salt-cake  stilutions  and  a  little  sulphide  ore  are  warmed  nearly  to  the 
boiling  temperature.  Bubbles  of  CO.,  attach  themselves  t.  the  sul- 
phides, travel  to  the  surface  of  the  solution,  <iischarge  into  the  air,  and 
drop  the  sulphides  into  the  pocket  on  the  under  side  of  the  tube,  as 
shown  in  the  annexed  sketch.  In  another  test  a  200-e.c.  beaker  is 
used  with  100  c.c.  of  3%  H^SO,  and  brought  to  nearly  boiling 
tcmiierature.  The  ore  when  introduced  into  this  yields  a  froth 
eoin[)osi'd  of  sulphides  supported  by  bubbles  of  CO..  In  ease  the 
ore  is  deticient  in  carbonate,  an  addition  of  as  much  as  :{';  of  calcite 
(U-  siderite  is  made.  The  froth  is  skimmed  with  a  spoon  as  soon  as 
it  forms.  We  have  noticed  that  a  great  deal  of  mineral  is  often 
lifted  partly  but  never  reaches  the  surface.     Con.sequently  extractions 


•Miiiinij  iitiii  .M  icH(i/ir  I'rrss.  Vol.  .\('\'l.  pa^e  414   (190.S). 

-H,  E.  Wood.     Trans.  A.  I.  M.  E.,  Vol.  XLIV.  pp.  6S4-701    (1912), 

•T.  .T.  Hoover.     'Concentrating  Ores  b.v  Flotation,'  1st  edition,  page 


TIIK   KI-()TATIOX    ruoCESS 


are  low,  although  the  grade  of  concentrate  ohtained  is  often  very 
good.  For  practical  purposes,  however,  the  test  is  not  of  much 
value.  A  better  test-machine  is  the  small  unit  shown  in  Fig.  57.  The 
acid  should  he  allowed  to  run  down  through  a  wet  ion  of  gard  n- 
hose  to  witiiin  an  inch  of  the  surface  of  the  ore  and  tlie  ore  should 


FlO.    55.      THE   WOOD    M\(IIINK. 


be  kept  stirred  witli  a  wooden  paddle  so  that  the  bubbles  of  CO. 
generated  by  tlie  action  of  tlie  acid  can  lift  the  sulpiiides  out  of 
the  body  of  the  i)ulp.  The  froth  formed  should  be  skimmed  with 
tno  paiuiir  as  ifist  TilS  ivirnic-.  Tnrii  niTorcu.  tirK-u,  Wvigiievi.  lUui  ciii(iiy/-tMi. 
Not  many  ores  yield  gracefully  to  this  treatment  and  slimes  give 
poor    extractions.     Fines    and    Wiltley-table    middlings    are    better 


TESTING  ORES   KOK  THE  FLOTATION    PROCESS 


281 


adapted,  and  the  preseiife  of  sideritc  in  tlie  pulp  is  desirahle.  as  it 
reacts  slowly  with  dilute  aeid.  From  1  to  ;{';;  ILSO^  is  hest  in 
testing  and  i  to  li%  solutions  on  the  large  scale  will  give  about  the 
siiine  results.  The  temperature  of  the  pulp  should  lie  maintained 
at  70°  C.  by  use  of  a  steam  jet.  Five  to  ten  pounds  of  ore  per  test 
is  necessary.  The  extractions  obtained  are  always  lower  than  in 
full-sized  units.  While  oil  is  not  necessary  in  th.s  process,  it  will 
greatl}'  assist  in  the  tlotation,  and  the  addition  of  a  small  amount  is 
often  of  much  assistance  in  test-work. 

jMecuanicae  frothing  as  developed  by  the  Minerals  Separation 
company  in  England  and  Australia,  and  modified  by  many  others, 
lias  been  one  of  the  most  important  methods  of  flotation.     Therefore 


Fig.  56.    test-tlhes  foh  flotation. 


the  lalwratory  nuichinery  that  has  been  developed  is  at  as  high  a 
state  of  perfection  as  any  such  machinery  now  in  use. 

The  Janney  machine  is  probably  the  best  designed  machine  for 
getting  reliable  quantitative  results  on  a  small  quantity  of  ore. 
Photographs  and  sketches  are  appended  (Fig.  5v8,  59,  and  60^.  It  can 
be  seen  that  the  agitation  compartment  is  cylindrical  in  shape  and 
that  its  top  is  surrouiuled  by  a  froth-box.  which  slopes  into  a  s|Htz- 
kasten,  where  the  froth  can  be  skimmed.  The  tailing  sinks  to  a 
return-hole  at  the  bottom,  passing  into  the  agitation-compartment 
again.  To  provide  good  agitation,  four  vertical  baftlcs  are  attached 
to  the  Willi  of  the  agitation-compartment,  a^jainst  which  the  pulp  is 


^"irirni  iV 


H" 


Ulli^      111 


\  j  rilllui'Vl 


lathing  or  with  a  coarse-mesh  iron  serei'ii  adds  to  tiie  thorough  mixing 
tiiat   the  imlp  must   receive.     The  two  impellers  are  on  a  common 


282 


Till:    Kl.dTATlHN    I'UOCK: 


sliiit'tinir.  wliidi  enter:;  the  inacliine  tlin>i|i;li  a  stiitliii'i-liox  in  the 
liotloMi  of  the  iiiaehiiie.  Tile  Idwer  iiiipeliei'  with  four  vertical  vanes 
is  suhiiier^'ed  ;  it  aiiitates  and  eiiinlsilies  the  pulp  while  the  upper 
inipeller,  likewise  witii  four  vi'rtieal  vanes,  aets  as  a  puiiii)  to  lift 
the  pul|)  and  heat  air  into  it.  A  iiuiiey  and  ))eit  conneets  the 
shafting;  with   a  variahlc-speed   motor. 

A  donie-sliaped  lid  is  used  on  the  iiiaehine.  A  small  hole  in  the 
to|)  of  the  dome  allows  the  introduetion  of  oil.  acid,  water,  or 
other  matei-ials  without  the  removal  of  the  lid.  The  lid  is  so 
eonstrueted     that     it     ean     lie    turned     upside-down     with     the    dome 


Wooden  Pao/a/e 


Froth. 


Fi(i. 


I'OTTKR-DKI.rR.vr    TKsr. 


oxlendiiifj  down  into  the  froth-hox.  and  in  this  position  it  ean  aet 
as  a  fuiniel.  The  dome  rests  then  on  the  top  of  the  agitatioii- 
eomparlment  and  no  froth  ean  eseaj)e  into  the  frothdjox.  This 
allows  a  period  of  a<jitatioii  of  the  pulj)  before  the  (loine-top  is 
turned  rigl.t-side  up  to  allow  aerated  pulp  to  overflow  into  the  frotli- 
liox  and  down  into  th(>  spitzkaston.  where  the  froth  ean  lie  removed. 

A  disrharKe-i)luiar  at  the  bottom  of  the  machine  allows  the  flushing 
out  of  tailiritr  after  the  test  has  been  eompleti'd.  So  careful  has 
been  the  desifjii  of  this  test-machine  thai  even  this  discharKe-plu<jr 
is  beveled  to  tit  flush  with  the  bottom  of  the  nuieliini'  and  thus  afford 
un  dead  spa<'e  in  which  the  solids  might  settle. 

i'lie  spii/kasieii  rs  iong  and  iiiirrow.  in  order  to  permit  a  <1eep 
froth  to  be  formed  and  to  travel  over  as  long  ,i  space  as  possible, 
before    I'enidiing   the    dischargt>.      This   tends   to   allow    mort>   of   the 


TKSTINC   iiKKS   liiK  TIIK   l-lnTATIoN    I'HOCKSS 


2s:i 


f'titraiiicd  >jr;iiitriii'  to  srtile  dul  of  tln'  iiiiinTiil  t'lutli.  'I'lii'  siili's  nt' 
the  sj)itzkiisti'ri  ;irr  of  liciivy  iihiti'-trliiss.  cai-li  fiistiiicil  to  a  iiictal 
frame  liy  nieaiis  of  screws  Tlic  w  niiis,'lit-iroii  slint't  projerts  tliroui;li 
a  t>rass  stnrti.it,'-lio\  ninl  is  Miiiporteil  liy  a  hall-lieii!  ini;  lieiicatli.  All 
the  other  metal  parts  are  of  east  ahiiiiiiiiiiii. 

The  small  virialile-speeij  itiotor  mav  he  of  cither  I).  C.  or  A.  C. 


Fic.  3S.     riiK.i.vNMV  .\IA(m.^^:.     <  ov  kk  i.wKiiiKii. 


type.  F.  a.  Jaiiney  reconniieiuls  the  ti.ie  of  a  (jieueral  Electric. 
»iiutiL-»\<iuini.  uircri-cui  leiil  iimloi-,  Loi-  'S-)<i  soils,  wilii  a  raied  tspeeti 
of  1700  r.p.m.  and  ]  lip.  Tiio  impeller-sliaft  )s  to  be  driven  at  1900 
r.p.m.  maximum  speed.     For  speed-eoiitrol  he  recommends  a  General 


284 


TIIK    KI.OTATKIN    I'KUCKSS 


Kicctric    (lin'ct-curroiif    li.hlrlii'ostat,    with    iiii    iiiiipciv    (•iii)acitv    of 
l.^,")  to  ().()(;:)  Jit  L'.Vl  volts. 

Ill  our  own  liilioratoiy  it  was  ili-siralil.'  to  iisr  the  onliiuiry  citv- 
liRhtiiifr  citciiit  of  110  volts.  A.  (  .     On  ili„t  ar,-oiint   \\v  liav  t'oiiiwi 


Fk;.    59.      Tllh    .lANNKV    .M.VdllNK.      (OVKK    ri'llK.llT. 

the   follouin^r  motor  satisfactory;     j-hp.   (ieii.'ral    Ekrtri(.-   repulsion 
induction  motor,  siiifrlc-pliase,  60-oycle.  with  full  speed  of  17»0  and 

•■•■•-       •  .:•:•;••:•-     ,;  ■       :  1- =      •.•,;:;«.     t;r     ^.I      aUipcrrS     at     22{J     Voil.-i, 

depending,'  iii)oii  the  voltage  of  the  current  supplieil  to  the  mai-hine. 
either  voltatre   iM'in-r  acceptable.      Speed-control    is  olitain.'d   liv   the 


TESTING  ORES  KOR  THE   FI/JTATION    PROCESS 


2HiJ 


use  of  an  ordinary  field-rheostat  in  series  witli  tlic  motor.  Siicii  a 
motor  lias  a  speed  varying  witii  tlie  load  and  with  the  voltage 
applied.  As  the  load  is  practically  a  constant,  the  speed  will  (lepen<i 
upon  the  amount  of  resistance  in  series  with  the  motor.  As  the 
majority  of  lahorafories  find  a  city  alterniitinK  current  more  con- 
venient to  ohtain,  such  a  motor  is  recommended. 

The  operation  of  the  machine  is  as  follows:    It   is  set  up  on   a 
l)ench  convenient  to  the  sink  and  to  running  water.     The  motor  is 


~sj' 


T ^■^'— 1 


Concerrtrafe 
Filttr   Cone. 


Fig.  60.    the  jan.nev  te.st  machine. 


set  up  one  foot  to  the  rear  with  the  switch  and  rheosiat  placed  so 
that  they  can  he  easily  reached  while  standing  in  front  of  the 
machine.  A  Jin.  round-leather  sewing-machine  helt  is  u.sed  for 
drive.  The  hearings  are  well  oiled,  the  stufKng-bo.K  is  pioperly 
packed,  and  some  attention  should  be  given  to  it  occasionally  in 
order  to  see  that  it  is  kept  screwed  tight  enough  to  avoid  leakage. 

Enough  clear  water  is  run  into  the  machine  to  barely  show  in 
the  spitzkasten  and  the  motor  is  started  at  its  lowest  speed.  A 
500-gm.  charge  of  ore  ground  to  at  least  48-mesh  is  added  and  the 
cuNti  ijiaiL-d  Oh  tiiL-  Hieii-iiiitc  in  ii.->  iiist'iicd  position.  (iSee  t'ig.  j)8.  i 
This  is  done  to  allow  thorough  mixing  without  circulation  of  the 
pulp.     All  or  part  of  the  oil  and   other  reagents  are   now  added 


'2tHi 


Tin:    Kl.uTVIIi'N     I'HOCKSS 


"I"'  'll''  lllntnr  l,r,,ut;lll  up  t,,  full  S|».,..i  f.,I-  .id  .s,.,.,„i,ls.  Tli,.  sp,r>\ 
IS    ;it,Mlll     low.  |V,|     In    III,.    MlillilllllMl    iuul    ill VIT    is    tUril.-,!    .,V(T    into 

IK  iipn-lil  ,,nMii„„.  .s,.,.  iMtr.  .-,!!.,  Tl„.  s|».,.,|  ,..  il„.n  n,js,.,|  ainl 
"■"'■'■  '"^  '"''l"'l  'l"(ini,'li  tlir  liul,'  in  111,.  t„|,  ,,r  i|„.  |„|  nnlil  il,r  frntli 

HI  thr  .s|Ml/k,isl..n   is  nnirly  at   tl vcrHow   lip.     Tin'  ultiinat..  sj I 

"I"  til,,  airitiil,,!-  uill  ,|,.p,.n,|  s„ni,.\vliat  iipi.n  tli,-  ,.|iara,.|,.|.  ,,f  this 
I'n.th,  as  .s,,ni,.  ,  ils  will  iriv,.  a  ,|,.,.p  p,.,.sist,.nt  r,-,,tli.  uhil,.  ,,11,,.,. 
fn'llis  ar,.  linn  and  l.rilti,.  aii,|  all,i\v  ,il'  nioiv  watiT  ll,•ill^'  a,l,l,.,i 
tn  111,,  ma, ■Inn,.,  as  u,.|l  as  more  vi<il,.|it  ajritali,,!!  in  ,.r,!,.r  t,i  ln.at 
"""■'■  ""■  '"'"  ""■  I'l'lp-  Til,,  fn.lh  may  ,.iili,.r  l„.  all,.u,.,i  t,,  tl,,u- 
out  <,f  til,.  spit/k;isl,.|,  „r  its  ,,un  uvi.^'lit  or  skiiiim,.,!  with  a  small 
w,M„|,.,i  j,a,l,ll,..  It  is  a  -,».,;  i,l,.a  |„  u,.t  tlu'  t.'la.s.s  si,l,s  „f  tli,.  'si.il/- 
with  wal.T  uhil,^  th,-  r|.,,tli  is  risintr,  s(i  that  ii,.ii,.  ,,r  th,.  fn,t||  „ill 
sti'.k  t,i  th,.  1,'las.s. 

Th,.  ,lurati,,ii  ,<\  ih,.  t,.st  is  aliuiit  live  niinuti.s  with  an  ,,r,.  that 
Hnats  ..asijy,  wliil,.  ,,tli,.|-  ,,r,  s  will  n.,|iiin.  a  (•,insi,l,.|alily  h>ni;,T  tiin,. 
to  alhiw  th,.  , -lit  rain, .,1  -.'anj;!!,.  t,,  s,.ttl,.  out  of  the  froth  lM.f,u'c  it  is 
(iis,.harj;i.,l  from  th,.  nia,.liin,..  In  su,.li  rast.s  it  is  h,st  to  h,,hl  ha,.k 
the  froth  until  its  appoaraii,'.-  sh,.ws  it  to  ))..  fairly  ,.h.an.  i{,.>:iniit.rs 
ar,'  lik,.|y  to  ilijnt,.  th,.ir  froth  with  to,i  iiiu,'h  fzaiifriu-.  In  a  larjrc- 
si/,.,1  ma, •hill,,  th,.  fr,iili  ,-Mn  trawl  ,iv,.r  from  tour  to  ,.i<rht  ffct'of 
s|)it/.ka.sl,.n  Im.Cuv  it  is  ,lis,■llar^',•,l.  wliil,.  in  this  t,.st-iiia,.hini.  it 
only  ha.s  a  trav,,!  ,,f  aliout  10  iii,.lu..s.  ('oiis,.(iu,.|itly.  the  small 
iiiachine  is  lialilc  to  yichl  ,.,in,-,.ntrate  of  too  low  a  t,.|ior.  Th..  .sami- 
ai)pli(.s  to  iiKLst  otht.r  iiiai'hiiu.s  for  makinjr  tests  on  tlotalioii. 

Th,.  con, .filtrate  may  In'  cau^'ht  in  a  pan  or  on  a  lilt,.r.  After 
the  test  the  iiiaehine  is  hrounrht  baek  t,)  l,)\v  spei'd  and  the  tailing- 
pliij,'  remov(.d,  so  that  th,.  tailiiiyr  ean  h,.  i.aiij:ht  in  a  pan  ,,r  hiick,". 
or  run  to  waste. 

If  it   IS  s,i  d,.siivd.  this  niufrh  ,-,ini.eiitrat,.  ean   h,.   |)iit   ha,.k   int,) 
the  ma,.|iine  and   tr,ate,l  in   th,.  same  way  as  the  original  sani|)l,.. 
or  the  e.ineeiitrates  lri,m  several  tests  eomhined  to  irive  ,.noiif;li  material 
for  re-treatment.     If  this  is  done  tluw  pnuluets  are  ma.le.  naimly  . 
A  'rougher'  tailintr,  to  wast,.. 
A  ,.|ean  <'oneentratt..  for  shipment. 

A  'ch.aii,!.'  tailin-r  ,ir  niid,ilin"r,  whieh  in  m-tual  i,ra,.tie,.  is 
ri-luri!,.,l  t,i  the  lieail  mai'hine. 

\\h(.|i  llu'se  eoii,litions  ari.  ohserv,.,!  H'sults  ,mly  slifrhtly  lower 
than  thos,.  jiossihle  with  a  Kig  mai'liine  ,.an  he  obtained.  A  t,..st  ean 
h>-  ruii  111  ii,,iii  .,  i,.  :;,i  minuies  in  sucii  a  maelmie  with  .'lOO  trraiiis 
of  ore  in  aiiythinjr  from  a  3:1  to  a  5:1  pulp.     The  plass    ides  of 


TE8TIN0  ORES   K'H!    IIU;   KI.oT  \'l'ln.\    I'ljcicK^s 


287 


tilt'  .s|)it/.kastcii  iill<iw  I'lii.M^  iili.siT\;iti(iM  of  tlif  i-miililiDii  of  tin'  troth, 
anil  tliis  is  a  ^'nat  advantaKf  to  tlif  li(f;iiiiicr.  'I'lic  .small  ainoiiiit  of 
ore  iicii  .s.sary  for  a  lest  i.s  a  iiuitlcr  of  I'onsiilcra'.ilf  coiivciiiciK.'i'  as 
fine  trriiidiiitr  of  the  ore  in  tlio  iMlmratoi'v  is  often  iiksomc.  Tlic 
aluinitiinn  castititr  is  little  eon-odiMl  liy  eitlier-  .eiil  or  alkaline 
cleetrolytes.     The  letni-n   of  |iul|i   ffoiii   the  'spitz'   to  the  airitatinj;- 


/rc^/r  Concentrate. 


"^-'Rubber  Plug 


/  Trough  for  frofh. 


~  Confraicfeii  Spif^kasfen. 

Kli:.    01.      .SKKTCH   OK   TlIK   I.YSTKB  OU   IIOOVKB    MAI  Ill.NK. 


Pulp. 


/  -^pelfer- 


Fig.  62.     anothkr  form  of  iioovkb  machine. 


compartment  allow.s  the  material  to  he  treated  until  all  mineral  has 
been  removed  wiiliout  stoppint;  the  maehine.  so  that  a  sinirle  i.'eat- 
nieni  yields  a  eieaii  tailing,  ilowever,  a  seeond  treatment  of  tlii.s 
'rougher-frelir  is  soiiietimps  neees.sary  in  order  to  get  a  high-grade 
eoneentrate.      Clean    tailings    generally    mean    only    medium-grade 


288 


Tin;    1-I,(>T\TI(IN    I'RorKSS 


eoiK't'iitrati's  lUu-   \o  .ntrjiitiMiciit    uf  j.';ni^'iic.   in   tln'   ri'iiKiviil   of  all 
tilt'  iniiicral. 

The  stutliiijr-liiix  in  the  hotldin  will  proljably  leak  if  not  watched. 
Ilowcvfi'.  this  driving'  of  the   iinprl'iTs  from   lifliiw.  instead  of   from 


Vu,.  i;:!.      I  III    iHiiiv  1.  It    \i  \i  in\F, 

aliove,    leaves   llie    top   of   tile    iiiaeliiiie    free    for   the  operator  and    is 

more  eoiiveiiient  ill  every  way.     This  is  of  iiiipoHaiiee  ill  a  laiioratorv- 
,,,.,,.!,;.,.,     ..,,1    ...iiT       ..-.,,        .1        ,.  ,.  ,     ,».        .  . 

'*"        ■■■-':      ••■::;     "   •.■  :;r.:-     :;;;■     :;:.;■     ,;:     ;;     \;  iilTiii^'-iM  iX.         ill     i*n  Jie-seaie 

iiiaehiiies  a  slnflinir-liox  underneath   wonid   not   he  tol. 'rated,  and   the 


TKSTIMi  OKKS   FOR  TIIK   FI,(lTATl(iN    I'KOCKSS 


289 


drive  should  l)t'  from  ahovi'.  We  would  iilso  sugg»>st  a  siieet-Jead 
constniclion  as  hi'iiig  more  easily  built.  A  J-inch  sheet-lead  is 
suffieicutly  ri};id  to  stand  )ip  well,  while  it   is  duetile  enough  to  he 


FlU.    G4.  TlIK    HOdVKK    \IA(  MINK.    SHOWING    STIHKEK. 

A.  Spltzkastt'n. 

H.  Agitation  compartnient. 

r.  Variiible-speed  motor, 

n  HpliiiiiinL'  linlts 

A',  Impeller. 

F.  Concent  I  ate  disihargo 


290 


TilE    FLOTATION    PKOCKSS 


worked  readily  into  tiie  drsired  siiape.     The  .j.n.its  arr  .a.sily  hi.ni.Ml. 
aii'l  it  is  auid-proof. 

TiiK  IIoovEu  .MAtiiiNi:,  so-called,  was  desi^'iied  after  a  test- 
iriachine  deserilied  in  the  second  edition  of  Hoover's  hook,  heing 
copied  from  one  of  Ly.ster's  patents,  and  has  l)een  imieh  eoi)ied  hy 
peoi)le  wishing  to  make  flotation  tests.  An  improvement  over  this 
eonstriietion  was  published  hy  Kali)h  Smith*  recently  (see  Kif?.  61), 
and  a  modified  sketch  of  the  same  is  shown  in  Fip.  fV2^  while 
I)hotographs  of  th.'  machine  used  for  a  while  in  our  lahoratorv  are 
shown  in  Fi-  6:i  and  64.  Eith.-r  a  varial.le-speed  ;notor  is  helt'ed  to 
the  pulley  that  drives  the  stirring  mechanism,  or  a  pair  of  cone- 
pulleys  on  a  constant-speed  motor  is  used.  This  construction  has 
been  popular  because  it  eau  be  ?i)adc  of  wood,  at  small  exi)ense. 
The  Janney  machine  will  cost  aliout  $100,  while  the  Hoover  machine 
can  be  built  for  a  small  fraction  of  that  amount.  :\rr.  Hoover's 
original  drawing  does  not  show  the  spitzkiusten  drawn  to  a  point, 
as  oidy  the  front  side  was  beveled.  Our  sketch  shows  both  sides 
beveled.  This  is  desirable,  as  it  eliminates  space  in  which  fine 
sand  can  settle,  and  tends  to  minimize  the  amount  of  pulp  lying 
inactive  in  the  spitxka.sten.  In  the  agitation-compartment  the  jnilp 
is  swirled  into  the  corners,  where  it  is  well  mi.xed  with  air:  hence 
the  baffles  sketched  in  the  Janney  machine  are  unnecessary.  One 
objection,  however,  is  that  uidess  the  agitation-compartment  is  very 
tall  the  pulp  lieing  swirled  into  the  corners  has  a  tendency  to 
.si)lasli  out,  and  a  lid  similar  to  the  one  on  the  Jaiuiey  nuichine  is 
desirable.  However,  it  is  difficult  to  attach  one  because  the  stirrer- 
shafting  is  in  the  way.  The  operation  of  this  niacliine  is  practically 
the  .same  as  that  of  tlu'  Janney.  e.xcept  that  without  glass  sides  on 
the  spitzkasten  it  is  hard  to  get  as  clean  a  froth.  A  charge  of  1000 
to  2000  grams  is  necessary  in  this  macliine. 

TiiK  Si.iDK  Machine,  as  shown  in  Fig.  65  and  66.  was  designed 
by  Hoover  and  perfected  by  many  others.  In  recent  jiractice  it  is 
motor-driven.  A  number  of  these  machines  were  given  by  James  M. 
llych'  to  various  universities  in  this  country.  Many  peojtle  favor 
;liis  apjiaratus  for  the  reason  that  they  have  had  little  opportunity 
to  use  any  otiier  design.  In  this  machine  the  agitator  is  driven 
from  below  thmiigh  a  slutruig-box.  as  in  tlie  Jainiey,  with  the 
consequent  freedom  of  the  top  of  the  machine  for  the  convenience 
of  the  operator.  The  top  half  of  the  niaclune  is  so  constructed  that 
it  can  be  slid  to  one  sii.li)    eiittinrr  <,fT  tl.n  f../itl.  P.,-......!  ;.,  .i :*,.*:,,_ 


'/■;.  .(  .u,  J..  Vol.  c.  paf-'o  lin.'i  (I'.n.'i) 


TKSTI-sG  ORES  K(IK  TIIK   FI.OTATKiN    I'KOCKSS 


2!»1 


from  the  {riiiiguc,  wliich  is  allowed  to  settli'.  The  operation  consists 
in  afritatini;  with  oil  anil  other  reagents,  then  a  period  of  (piiet 
during  wiiicii  the  froth  eolleets  at  the  top  while  the  fran«rne  sinks. 
Two  windows  in  the  side  enahle  the  observer  to  see  when  the  traiifrne 
has  subsided  sutTieiently  to  allow  the  top  half  to  be  slid  along  the 
rubber  f.',isket,  cutting  oti"  the  froth  from  the  remainder  of  the 
[Hilp.  The  time  neeessary  for  the  settling  of  the  gangue  is  suflfieient 
for  much  of  the  gangue  to  separate  from  the  froth,  leaving  only 
clean  sulphides  in  the  froth.  This  element  of  the  machine  has 
made  it  of  some  vjilue  in  testing  flotatioTi  oils,  but   in  a  weak  froth 


FlO.    65.       THE    SI.IDK    .MACHINE. 


much  of  the  sulphide  mineral  also  settles  out  and  is  lost,  so  that 
the  test  results  with  this  machine  often  show  unnecessjirily  low 
extractions  and  a  high  grade  of  concentrate.  On  the  other  hand, 
when  conditions  are  adjusted  to  give  a  froth  persistent  enough  to 
hold  all  the  sulphide  mineral,  considerable  gangue  is  entrained  in 
the  stiff  froth.  Further,  after  skimming  one  froth  we  find  it  neees- 
sary to  add  more  water  and  start  the  machine  again  to  make  more 
froth.  It  is  hard  to  make  the  slide  machine  give  a  high  extraction 
with  only  one  agitation.  The  intermittent  character  of  such  work 
and  the  time  necessary  to  wait  while  settling  arc  disadvantages  that 
make  the  Janney  or  the  Hoover  macliines  of  greater  utility,  in  our 
opinion.  The  parts  ai'c  of  cast  aluminum  with  a  rubber  gasket 
between.     A  chartre  of  fjOO  to  1000  grams  of  ore  is  used. 

As  regards  the  fineness  of  crushing  in  laboratory  work,  material 
ground   as   fine   as  20()-mesh   will   yield   liigh   extractions  with    much 


292 


I'llF.    I-I.MTATION    I'liOCESS 


Longitudinal    Section 
Fl(J.    Gfi.       IIIK    hl.IDK    MAIHINE. 

A.  rpper  part  of  cell. 

('.  Lower  part. 

Ji.  Riibljer  cushion. 

D-  Tail  to  picvent  leaUaRe  of  froth. 

/v.  Auitator. 

/•'.  Hole  for  withdrawal  of  tailinsr. 


grejitiT  case  tliaii  cdars.-r  material.  It  is  i)o.';.silile  to  «,'et  aeceptahle 
work  ill  some  cases  with  material  as  eoarse  as  4()-mesh  on  coiulitioii 
that  there  is  a  considerable  portion  of  the  same  material  in  tiie  slime. 
For  or.Iinary  laboratory  work  a  convenient  size  is  80-mesli,  unless  poor 
extractions  are  olitained. 

I  The  (ieneral  Kn^'inecrinpr  Co.  at  Salt  Lake  City  and  the  :\rine 
&  Smelter  Supply  Co..  at  Denver,  sell  flotation  macliim  s.  So  docs 
the  Denver  Fire  Clay  Co.,  which  makes  a  modified  Hoover  machine 
The  .Jo.shua  Ilendy  Iron  Works,  San  Fraiici.sc.,.  makes  machines  tor 
the  Minerals  Separation  company. — Ennon.] 


TKSTINd  OKE.S  KOK  TllK  KI.OTATION    l'K()CES> 


•2'.Ki 


TESTING  ORES  FOR  THE  FLOTATION  PROCESS— II 

l?y  O.  ('.  I{\i.sT()N  and  (ii.i;N\  L.  Ai.i.kn 
(From  the  Minimj  and  Scimtifiv  Press  of  January  8.  Utl6) 

Skpahatohy  Fr.NNKi.s.  ]>iirin^  tlic  past  year  an  artii  I.  on  prai-tice 
in  Mcxifo'  nicntioncd  tlic  fact  tliat  ii.iicli  of  thr  preliminary  testing 
on  the  ore  was  done  in  se|)aratory  funnels,  in  \vi:ich  the  ■  harges  of 
pulp,  oil,  ete.,   were  shaken,  after  wliicii   t'  ■•  .'oek  at    the  bottom  of 


Fk;, 


Kl'AKATING    KIN.NKI.. 


tlie  funnel  was  opened  and  the  tailini;  run  into  a  seeond  separatory 
funnel  for  further  flolation  tests,  the  eoek  being  closed  in  time  to 
cateh  the  froth.  The  versatility  of  e.xperiment  permi.ssible  with 
the  use   of  ,sueh   apparatus    ( Fig.   (57 1    is  e<.inmendabh>.      Obviously, 

thisi     :ifr.'iiure!noot     i«    nt^tui     ii\     tlio     c-mw*     .-.1^  I.,,.*:.^,.^     ,.*.     ;^     4)  ..      .i;.i„ 


5Af.  if  N.  P..  Vol.  CXI.  iiase  11.'2  (.July  24,  191.5) 


2!)4 


'11  IK    Kl  OTATIoN    I'KdCKs 


machine  ...xnpt  Iliat  .s,.|mrat.,iy  lu.in.ls  an.  si,„,.l,.  and  iiu-xprnsiv,. 
hi.MoHK  .M^,■^l^K.  As  far  as  we  know,  no  small  test-niaHiine 
l"r  the  Klinniv  ,,r„ress  has  .-(.nie  mt.)  ,.o,u.,mn  use  on  ae,-o„nt  of 
the  lael  that  thr  i.mI|.  nnist  he  lifted  throu-h  a  f.ihe  eonespondin- 
^ni  h.n-th  to  tiir  rnlmnt.  „f  water  e.|iiiva!ent  to  haroiiirtri,.  j.resswn" 
J  his  niakrs  an  awkward  lal.oratory  machine.  .Mr.  Hoover  (•>|.d 
.■<lition  pa-e  !l,s,.  deserilH-s  ■■illustrative-  e.xperiii.ents  with  the  pulp 
111  a  hottle  .•oniKM.ted  with  a  water-i)nnip  for  i)n,dueiuK  a  vaeuui.i 
Imt  no  (luantitative  method  of  this  kind  has  heen  <levloj)ed. 

Other  mis...llanrous  frothint;  te.sts  are  in  the  literature  hut   most 
of  th..m  are  merely  ••illu.strative. "     Puttin-  a  ehar-ie  into  a  sn,la- 
wat.'r  siphon,  pumpin-  in  air  lo  diss<,lve  the  water,  ami  then  releasing 
the  .■har.;..  into  a   heaker  ^'iv,.s  niee-lookin-   froth.      In  .some  of  the 
lawsuits    s.|uare    f.dass    eandy    jars    (Fisr.    (iS ,    with    a    ni.,tor-driveu 
iinpeller  have  hee,,  used  to  show  flotation  phemmiena  in  eourt      In  a 
'veent   I-.  S.   Patent    (  .\...   1  .ir,.-,.8:i61   taken  out   hv  T.  M.  Owen    .me 
nt  the  en-ineers  of  the  Minerals  Sei)aration  eompany,  is  a  sketeh  of  a 
.simi>le  test-ma.-hine  made  „f  .•>„  ordinary  2i-litre  aeid-hottle.      (See 
Fi.L'    (i!l.  I       This   e(,rresponds   to    the   suh-aeration    tvpe   of    machine 
and  IS  recommended  hy  Jlr.  Owen  for  test-work  wh..n  such  a  tvpe 
"t    machine  semis  neces.sary,  as  in  ditf.Tential  flotation.     Air  is'le.l 
into  the  pill,,   throiifrh  the  stopper  in  the  hottom  and   heaten   into 
the  jnilp  hy  the  impeller.     The  four  large  hafties  ahove  the  impeller 
prevent  the  swirlinir  of  the  imlp  from  risinjf  through  them,  so  that 
there   is   a  Muiet    xone   in   the   top  of  th..   machine   where   the   froth 
can  collect.     On.,  frivat  heauty  of  su.'li  a  machine  is  that  aiiv  froth 
l.)rm<..l  will  ris(.  imm...liat..ly  to  the  dis.'harcje.     IIow,.ver.  we"li..lieve 
that    th.-  .lanih-y  an.l    Hoover  ma..|iin..s  are   the   m.ist    useful  of  the 
iiie.'hanically-airitat.'d  typ.-. 

P.M:r.\iATic  Fi,..TATi...N-.  Amonj;  th..  .lirtVrent  piu'iimatic  macliim>.s, 
as  far  as  w,.  ar..  a.-.|iiaiiit..,l.  th.'  CaHow  t..st-maehine  is  the  onlv  one 
of  lal.oratory  si/e  that  has  heen  much  .levelop...].  It  is  merely  the 
commercial  ('alh.w  ma..hin..  r..du..ed  in  siz..  (see  Ki<r.  70.  7],  ami  72  1 
Lat.T  .l..v..|,>pmeiit  in  the  laboratory  u(  th,.  (;<.neral  Engin..i.rin2  Co.. 
in  Salt  Lak..  City,  has  resulted  in  the  repro.lucfion  of  th..  whole 
plant  m  miniature  (as  shown  in  Fig.  72i.  with  a  Pa.-hu.-a  mixer  a 
roufrhinf;-.-..|l.  .•l..anin--.-..ll.  va.Mium-filter,  an.l  sand-pump  to  return 
mi.l.llinsr  to  th..  Pa..hii..a  mi.xvr.  As  s.-,..,  in  the  .Irawinj;.  the  pulp 
IS  niix...l  W..11  ui  a   Pa,-hii..a  tank  of  small  sizo.  overflowing  into  the 

••••,,•••:    :!-:.-,;.-;::  ;;!i.       i;ir   Jailiiifi   rr./iii   tills  rougiier  jjoes  to  a  saiul- 
pump   an.l   is   ivtiirne.!   to  th..   Pai-huea,      The   froth   is  tr.>ated   in  a 


TESTINU  OUES  KOK  THE  FLOTATION   PKOCEiSS— II 


AlK    CONNCCTION 


Jx 

Pol  L  e  yj.,./^*-^-!      < 


T" 


fSvPPOf^T 


u 


u 


<10  Agitator 


45  A  a  iTATOR 


R0TATIN6 

Hollow  Shaft 
1   TO  Aonrr  Air 


Support 


AtlTATOR 


S<?C.ARE 

Gl  ASS 

Jar 


295 


Fig.  68.     the  squabe  oj.a-^  .jak  machine  fob  making  flotation  tests. 


296 


Tin:  Ki.iiTvTiiiN   r;i(«'Kss 


seeo.Hl   n,u     small,-,-   ,.n,-,nMat.,-ri.,t.,,nn    m„t.    irivini:   ,-,    ,-„, „trate 

hat,   ..v.-rflows    inin   a ,|i,un-y    lal.„ral.,r.v    va,-,.u,n-!ilt,.r   a,-t„ated 

hv  a  wat.-r  <.i-  ,-,.s].natn.ir  piuii,,  Th,-  tailing,  fn.in  tlw  ■.-l.-an..,--,.,-!!' 
eoHs.sts  or  a  „n,:,lli„f,  ,1.,,  I.K.-uis.-  Hows  to  tl,.-  san.l-,,n,np  and 
Mai-k  to  till-  l'a(-li;i(-a. 


Pulley. 


t,.^- Glass  Jar. 


-4Baffles. 


Impeller. 


^'ooc/en  Cork. 
Pipe  Nipple. 
Checkyalve. 

/^ir  Inlet. 


Fll,.    <;it.       CIWhN     1KM-.\IA(   lll\K. 

A  i.ovi,-,.  will  hav,-  „o  small  ,litTfi,.„lty  in  operatin^r  su,-h  an 
installat.on,  as  ,!,..,-,.  „-..  a  n,,,,,!,,-,-  of  ,hin,-s  1o  I,..  k..p,  i„  o,„.,-..,io„ 
•'"  "'"  ■'^""''  """■•  ''■'"■  '"i-^""-,.  of  on-,  watrr.  oil.  an,|  anv  oth.r 
roagents  is  t,.,I  ..iH,,.,-  mto  ilu.  suction  of  tlir  san.i-n,nm,  or  i.,t,.'tt,.  f.. 
ol  fn.  I-a,-l,u.-a  affr  air  has  Im-..,  start,-,!  into  th,-  various  n,a,-liin.-; 
n,..   ov.i-flow    Iron,    th,-    I'a.-h,i,-a    into    th-    ro,i^.l„.r-,-.-ll    a,-,-„niiih,tes 


TKSTI.Ni,  (IKK-    l()|{  TiiK    Kl.nT ATIoN    I'liof'Kss II 


297 


until  a  ni,...   fn.tl,   ,s  „iiiK  up  an.l   nearly  ..vrtlowi.,-      Then  the 

tailinfi-.lisclu.w  valv..  ,.n  ll„.  nn.-l,,.,-  is  -ra.lnallv  ,,..,1  a.ui  fn.tl, 

allowf.l   t..  ..v.Ttlow   rn,ui   th, II    into  tl„.  •r|,.an..r'-,...||       It    is  l,..st 

to  f:,t   ,M(.st  „f  ,|„.  ,.|,,Pir,.  .-iivMlatiM-  iM.fn.v  „„.,  I,   r,„MVM t rat-- fiot I, 


VwS^J^ 


Fk;.  7n.     rut;  tAi.i.ow  (  ki.i.  (kauiv  k.umi. 
-4.     Froth-overflow  liuinders. 

B.  PM!n-fu.,d    !n   :!■>  ••.lu:;!.;-.t  = 

C.  Air-atonii/.iiit;  lilaiiUet. 

D.  Concentrate  discharge. 

K.     Compressed-air  feed  to  wiiid-lioxes. 


298 


TIIK    FLOTATION    I'liOCKSS 


is  iilliiwcil  to  oM'i'tlou,  till'  (iv»'i-f!i)\v  (if  t'rotli  hi'injr  cniitriillfcl  hy 
tilt'  main  iiir-viilvcs  Irjidinj;  to  cacli  unit.  After  i\.v  valves  into 
the  iridiviilual  wiiul-iidxes  lieneatli  the  laaeliiiie  have  heeii  oiiee 
adjusted  they  should  never  lie  disturhcd,  and  all  eontrol  of  air 
.sii|>i)li('d  should  lie  at  the  valves  in  the  main  ])i[)es.  When  every- 
thing? is  K"'"f?  \vell,  the  air-pressure  in  the  eleaner  can  he  inereased 
until  ('oneentrate-frolh  is  overflowiiiff  into  the  vaeuum-filter.  A 
wooden  i>addle  to  stir  any  settled  material  in  the  flotation  cells  is 
of  value,  ius  well  as  a  snuiU  jet  of  water  from  a  ruhlier  hose  for 
washintr  eoncintrate  alonjj  the  froth-launders  and  for  licatin<;  down 
froth  when  oeciusional  too-violent  nishes  of  froth  from  the  cells  take 
place,  After  a  test  is  coniplete  the  l>ul|)  should  lie  drained  coiiipletcl\' 
from  all  j)arts  of  ttie  machine  while  the  air  is  still  hlowin^.  so  that 


7b  Vacuum   

-*    Pump.     L^ 


FUi.    71.      CAI.I.OW    fKST   SET. 


solids  will  not  settle  in  passages  or  clog  the  canvas  blanket  in  the 
cells.  Only  practice  will  allow  anyone  to  get  reliable  results  with 
this  machine.  A  watch-glass  for  catching  and  panning  occasional 
samples  of  froth  is  another  necessary  au.xiliary  to  this  equipment. 
The  cost  of  installing  such  a  set  of  apparatus  is  from  $100  to  $150. 
At  least  1000  grams  of  ore  is  required  for  a  test  and  about  30  minutes 
to  1  hour  is  spent.  It  can  be  seen  that  nothing  but  a  firiished  concen- 
trate and  a  tailing  arc  obtained  or  a  middling  product  may  be  left  in 
the  eleaner  cell.  This  middling  may  be  assayed  as  such  and  calculated 
into  the  concentrate  and  tailing  or  its  sulfihides  may  be  panned  out 
and  added  to  the  concentrate.  The  machine  is  said  to  give  result.^ 
closely   paralleling   those   obtained    with    larger-scale    a])paratus.      A 


TKSTlMi  ()|{i:s  FOK  Tin;   FLOTATION    I'UnCK-s       II 


•»;iit 


Sdurec  of  sui)|)ly  of  coiMin-csscd  air  at  .'i  to  .')  lli.  prr  s<|    in.  is  ii< ssary 

and  the  liiaili  valves  on  tlit>  air-pipe  leadiiijr  to  eacli  rnaeliine  shoidd 
lie  some  ty|)e  of  needle  valve  in  order  to  ensnri'  exaiM   'nntrol. 

In  ti'stint;  [)raetiee,  tlie  air  lift  type  of  niiddlintr  ntnrn  has  li.en 
found  niore  salisfaetory  tlian  tl 'ntrifiii,';il  pump  sliown  in  Fie.  71. 

l.\r,«iUAT(iKV  .Maniim  I. ATKINS.  Tnrniinr  Irom  the  description  of  the 
niaehines   used    to    the   operations  on    the   ore    het'ore   and    after   the 


: ■ 

- 

"  ^V'' 

i 

:  i 

•  * 

M 

1 

\ 

Pig.  71'.     <  allow  test-ma(  hink  with  I'AeiucA  mixkr. 

A.  Pachuca  mixer. 

B.  Pulivfeed  to  air-blanket. 

C.  Needle  valve  iiir-oontrol. 

T>.     Blanket-elanips  for  quickly  renioving  blanket 

for  cleaning. 
F..     VVind-boxe8. 


flotation   operation,    we   have   in   general   the    problems  of  crushing 
the  ore  and  of  drvi'ig  the  frotli-conceutrate. 

As  a  rule  laboratory  machinery  tor  the  pulverization  of  ore  is 
of  the  dry-grinding  type,  with  the  exception  of  small  hall-mills  that 
can  crush  from  1  to  ino  lb.  charges  in  the  wet.    Consequently,  most 


300 


TlIK    FI.OTATIiiN    rKOCKSS 


pt'ople  (iliirt  with  wcIkIkmI  ihurKi's  of  tiiiely-Krouiiil  dry  ore,  ii  known 
(|ii!inlily  (if  water,  nl'  nil,  mni  of  acid  or  alkali.  Our  experience  has 
been  that  most  ilry-Kroumi  ore  must  he  treated  in  an  ueiditied  pulp 
to  get  good  Hotatiori.  Doiihtless  the  surfaces  of  sulphide  particles 
become  somewhat  oxidi/.ed  in,  or  shortly  after,  dry  Krindin^  uiul 
tilt  function  of  the  acid  would  be  to  cleati  the  slijfhtly  oxidi/ed 
Burfai'es.  Wet  grinding  usually  does  not  call  for  so  mui'li  a<id.  In 
nearly  all  laboratory  work  finer  urinditi^'  than  is  used  in  practice 
sevniH  to  be  necessjiry.  This  may  possibly  be  due  to  the  snui"  r 
amounts  of  froth  that  are  formed.  Such  small  (piantities  of  froth 
cannot  form  layers  as  deep  as  those  made  in  the  large  machines. 
If  a  bit:  particle  of  sulphide  can  be  entrained  with  a  numbi  r  of 
smaller  particles,  it  can  be  floated,  but  with  a  thin  froth  the  chance 
of  such  entraiiimcnt  would  seem  to  \n'  less.  Some  experimenters 
have  infonned  us  that  they  were  able  to  float  even  as  large  as 
30-mesh  material,  but  our  own  experience  is  that  6()-mesh  nmterial 
is  often  hard  to  float  with  any  chance  of  getting  a  high  extraction, 
while  the  operation  is  perfonuod  with  much  more  ease  and  exiu'dilion 
when  the  ore  is  crushed  somewhat  finer. 

Wet  grinding  is  more  desirable,  as  it  parallels  conditions  in 
practice,  where  most  of  the  finer  grinding  of  ore  is  in  t'hilean,  tube, 
and  other  mills.  However,  wet  grinding  is  harder  to  nuinipidate 
in  a  small  laboratory  and  requires  more  time.  The  dry  weight  of 
the  feed  to  the  flotation  machine  must  he  known;  hence  a  weighed 
charge  of  dry  ore  crushed  to  a'lout  10-mesh  can  be  introduced  into 
a  porcelain  or  iron  pebble-mill  for  grinding  and  ground  for  tiie 
length  of  time  found  necessary  to  reduce  the  pulp  to  sufficient  fine- 
ness— 15  minutes  to  24  hours.  The  charge  can  then  be  poured  and 
washed  through  a  coarse  screen  (to  retain  the  pebbles)  into  a  bucket 
and  thence  into  the  flotation  machine.  The  oxidation  of  sulphide 
suvfaces  is  thus  avoided,  but  separate  grinding  of  each  charge, 
in  order  to  know  its  exact  weight,  is  rather  tedious  and  requires  a 
number  of  small  mills  if  many  tests  are  being  run,  on  account  of 
slow  speed  in  grinding.  A  mill  with  iron  balls  rather  than  pebbles 
is  of  greater  service.  It  is  possible  to  introduce  the  flotation-oil  lieforc 
grinding,  to  be  sure  that  it  will  be  thoroughly  mixed.  Vnr  thick 
viscous  oils  this  is  highly  beneficial,  as  a  ball-mill  gives  about  the 
best  conditions  for  agitation  and  mixing.  Usually  1  to  2  lb.  charges 
are  used  and  a  smaii  inipoiahuy  iniii  oi  the  ADDe  type  srrv;;-;  v.c;;, 
altliough  a  good  mill  can  be  made  with  a  10-in.  length  of  8-in. 
iron  pipe  and  two  lieavy  iron  caps  for  the  same. 


TESTING  OBEH  ►OH  THE  Kri<jTATroN    CKOCESS  —  U 


:m 


cc 


PrHctirc  ill  Miir  liilionitory  lias  Ihtm  "tundunli/.i'd  to  ii  iiiiniiituri' 
Kynitory  cruHliiiig  to  lO-iiu-sli,  splitting  into  wcif^lRMl  saini)lfS  kept  in 
paper  bags  and  ri'duccd  to  smaller  size  li\  litlicr  wtt  or  dry  Krieidinj? 
a«  orcasion  demands. 

A  short  stemmed  tin  funnel  al)oul  tl  inelies  in  diameter  with  a 
one-iiieli  oj)ening  is  t'ouiid  to  he  ahout  the  most  eoiivenieiil  means 
of  jjoiiriiii?  a  ehar^'e  of  ore  into  n  lalmratory  flotation-mai.-hine. 

The  iiieasuriiijf  and  testiiij;  of  Hotat ion-oils  in  the  lahora- 
lory  has  h  'c'l  very  inexact  in  many  instanees  witnessed  by 
U8.  It  is  eommon  praetiee  to  eiiuiit  thf  huiiiher  of  drojis  of 
oil  falliiif?  from  a  small  piece  of  glass  tuhiiiK  We  are 
using  a  Mohr  pipette  of  1  .  c.  total  ea|)aeity  for  metusiire- 
meiit  of  the  amount  of  oil  used  in  each  test.  Such  a  pi|)ette 
is  shown  in  full  size  in  Fig.  73.  It  will  be  seen  that  this 
l>ipette  aHows  measurements  of  the  oil  to  the  nearest  0.01 
c.e.,  which  is  as  close  as  will  ever  be  desired.  If  the  density 
of  the  oil  is  known,  the  volume  as  mea.sured  by  this  method 
is  quickly  converted  into  tlii'  weight  of  oil  usc-d. 

The  t>  sting  of  oil  samples  for  flotative  power  is  a  matter 
that  needs  standardizing.  It  is  desirable  to  classify  oils 
according  to  flotative  power,  but  just  how  to  do  this  is  not 
exactly  clear.  A  unit  of  ■flotativeness'  might  be  established 
and  each  oil  referred  to  that  unit  in  terms  of  percentage. 
Jiut  it  has  to  be  remembered  that  the  best  oil  for  one  ore 
may  not  prove  to  be  the  bist  oil  for  another,  although  two 
such  series  of  oils  might  roughly  parallel  each  other.  For 
any  given  ore,  it  would  be  permissible  to  make  such  a 
measurement  on  a  st  ries  of  oils  and  gn)up  them  according 
to  some  definite  standard.  A  standard  oil  might  be  chosen 
and  the  value  of  a  second  oil  expressed  in  percentages  of 
the  flotative  power  of  the  first  as  determined  by  using 
equal  quantities  of  the  two  oils  in  tests  on  an  ore  under 
identical  conditions.  This  test  could  not  ))e  fair  for  the 
reason  that  clifferent  amounts  of  two  different  oils  are 
necessary  to  accomplish  the  same  results.  Further,  the 
conditions  of  acidity  or  alkalinity  might  favor  one  oil  and 
handicap  another.  If  we  mea.sured  the  amount  of  oil 
necessary  to  give  a  fixed  percentage  of  extraction  the  first 

of   the   above   ohiectinna   wnnl.1    Ko   outicH...!     l,..t i!»: 

" ■••"-    t:;;:juiiit;!i:-;  rj 

of  acidity  or  alkalinity  could   make   the   test   unfair   for  ^ . 

some  oils.    Hence  the  dilemma  as  to  a  standardized  test  of        ^^°'  '^' 
a  flotation-oil.  "'""'"' 

PII'KITK. 


z3 

- 

h 


302 


THE    Fl.dTA'i'IllN     riiOCESS 


No  single  test  could  difiiiiti-ly  i)lace  an  oil  in  any  sclionie  of 
classi ligation  and  iiothiii^r  <  an  he  done  imt  run  a  scries  of  tests  using 
varying  anK)unts  of  the  oil  to  be  tested  and  with  varying  acidity  or 
alkalinit\.  The  temperature  of  the  \m\]>  iiuist  be  kept  constant 
although  it  has  a  minor  etVect. 

Coutts  gives  about  the  only  directions  on  oil  testing  that  are  to 
be  found  in  the  literature  of  tlie  subject".  lie  states  rightly  that 
the  first  tiling  to  do  with  an  oil  is  to  measure  its  density,  for  future 
eab.'ulations.  as  it  will  be  measured  by  volume  in  the  laboratory 
and  nuist  latei-  be  reduced  to  weights.  He  recommends  the  use  of 
a  burette  for  measuring  the  oil.  but  we  favor  the  ilolir  pipette 
mentioned  above.  Tie  chooses  a  standard  ore  on  which  all  tests  are 
to  be  run  and  classifies  three  ditl'erent  kinds  of  standaid  tests: 
(1)  for  mixed  sulphides.  (2i  difTerential  sei)aratiou.  and  ('■])  flotation 
of  copper  and  iron  sulphides.  He  states  that  oils  high  in  phlanderene 
have  proved  best  for  differential  separation  of  zinedead  sulphide 
ores.  While  this  is  helpful,  he  d'  .s  not  state  just  linw  the  oils  are 
to  be  cla.ssitied  after  tlie  tests  liave  been  made. 

INIuch  work  with  oils  is  needed  in  order  to  determine  if  there  are 
any  definite  constituents  in  oils  that  give  them  flotation  power. 
Research  is  also  needed  in  the  preparation  of  oils  from  the  wood, 
coal,  and  mineral  oils  in  such  a  manner  that  they  will  have  maximum 
etTfieiency  in  flotation.  Work  on  this  subject  has  been  initiated  in 
our  own  laboratory  and  it  is  known  that  several  of  the  larger 
companies  have  employed  oil  chemists  to  look  info  sueli  ])roblcms. 
We  nndervtand  tliat  most  excellent  ,vork  is  oeing  dom'  on  methods 
of  modifviig  and  reconstructing  oils  that  can  be  had  cheaply.  By 
this  we  mean  more  flian  mere  mixing  of  a  good  flotation  oil  with  a 
eb.eaper  non-selective  oil.  Sulpluitiaf ing  the  oils,  dis.solving  them 
in  acicls.  dis.solving  modifying  substances  in  the  oils.  etc..  ar(>  some 
of  the  ideas  being  tested  with  varying  success.  It  is  on  account 
of  all   this  ,iil   testing  that   considerable   progress  has  been   maile  in 


flotation    during 


past    year. 


that    now    most    of    the    larger 


eiinipaiiies  ,•'.:•;■  using  cheaper  oils  than  a  year  ago. 

When  starting  to  work  with  a  new  ore.  ther(>  is  needed  a  rai)id 
qualitative  iii.-thod  of  choosing  an  oil  tliaf  seetns  well  adapted  to 
the  flotation  i>\'  the  ore  in  i|ue.sfir'i.  Such  a  scheme  is  in  use  in 
the  I.Mhoratory  of  the  deiicral  EnErineering  Company  at  Salt  Lake 
rifv.  'I'lieir  (lualifative  tester  is  desiencd  to  test  oils  for  use  in  the 
('■.ll.uv  iiiiPiu.intic  flota'ion  ceil  and  consists  of  a  urlass  tube  of  about 


nj.  Coutts.      !■:    .(    .1/    .',  Vol.  XC!X,  li:mo  KtTO   (UHr.V 


TKSTI.\(i  OHES  FOH  TIIK  II,()TATI(».\   I'HOCKS 


.•{(Ki 


two  inches  diameter  and  two  t'ei-t  lon^^  {F\'^.  74.)  This  can  he 
set  on  end  and  closed  at  the  hottom  with  a  one-hole  rubber  stopper 
through  which  passes  a  glass  tube  into  a  small  canvas  bag.  The 
small  hubltles  of  air  coming  througli  tlie  canvas  are  similar  to  those 
used  in  large-scale  machines  and  can  be  observed  through  the  glass 
walls  of  the  tube.  With  some  pulp  ii.  the  tube,  oils,  acids,  .salts,  etc., 
may  be  added  in  very  short  tests  until  the  proper  appearance  is 
obtained.  An  overflow  lip  is  provided  i  case  it  is  desired  to  e.xaminc 
the  mineral  in  the  froth.  A  slight  adjustment  of  the  air  will 
provide  an  ample  overflow  of  froth. 

Disi'os.vL  OF  THE  Frotii.     The   handling   of  the   flotation    froth 
in   the  laboratory  finds  difficulties  which   are   reflected    in   practice. 


^ 

;.\V^ 

J 

Tuhe 

pl>'/> 

.^A ;  • 

y\ 

Fig.  74.    qu-M-itative  on,  tk.stkk. 


It  is  often  very  slow  to  settle  and  filtei-s  with  difficulty.  A  vacuum- 
filter,  connected  with  a  laboratory  a.spirating  pump,  is  a  very 
convenient  method  of  getting  the  concentrate  out  of  the  froth.  A 
large  porcelain  Buechner  funnel  fitted  into  a  filtering  flask,  as  shown 
HI  F'g.  60,  is  used  at  present  in  our  laboratory.  A  copper  vacunm- 
fiiter  of  much  the  .sjime  type,  provided  with  a  porous  false  liottom 
of  acid-proof  wire  cloth,  resting  on  a  punched  plate,  is  shown  in 
Fig.  71  of  the  Callow  test  set.  Filter-papers  ca.:  he  laid  over  the 
bottom  of  either  of  these  funnels  to  coUect  the  concentrates,  and 
the  vacunm  beneath  sucks  out  the  water  and  oil  of  the  froth.  Such 
a  tiltcf  can  be  placed  under  the  froth-discharge  of  a  flotation  machine 
so  that  a  fairly  dry  cake  of  concentrate  is  ready  for  further  drying 
at  the  end  of  the  flotation  test.  Ry  loosening  the  outer  rim  of  the 
filter-paper  and  then  turning  the  funnel  upside  down  over  ;.  pnii,  (lie 
filter-paper  with  the  concentrate  can  be  dropped  into  the  drying-jian 
by  gently  blowing  into  thi'  stem  of  the  funnel.  This  is  set  aside  in 
a  warm  place  to  dry  and  later  weigjied  against  a  filter-paper  tare. 
Tf  it  is  desired,  tiie  froth  can  lie  collected  in  a  gla.ss  beaker  or 


304 


Tlir.    n,()TATI(IN    I'UdCKSS 


ether  vessel  and  allowed  to  .stand  ovei'iiiglit.  A  layer  of  elear 
water  can  then  he  sij>iioned  otf  and  the  tiuek  pulp  remaining  liltered 
or  dried  direct.  In  some  lahoratories  the  froth  is  dumped  onto  a 
shallow  pan  on  a  hot  i)late  and  tiie  water  evaporated.  Oeoiusionally 
such  a  sample  of  froth  will  he  left  too  loiif?,  and  will  he  ifjiiited 
and  roasted.  We  once  used  a  innnbered  set  of  shallow  ])ans  t'or  such 
evaporations  but  i)refer  filtering  before  drying  the  precipitate.  A 
numbered  tag  is  now  put  in  each  pan  along  with  th"  cake. 

The  ])roduets  coming  from  the  flotation  machine  should  be 
watched  closely  and  occasionally  panned  or  e.xannned  with  the 
microscope  to  see  what  kind  of  work  is  beiin,'  done.  This  is  t'airly 
Ciisy  to  determine  as  the  sulphides  ,;i\  mo.  ')f  them  distinguisiied 
easily  from  the  gangue  under  the  niier's  oe.  and  likewise  gangue 
particles  in  1hc  froth-con. •ciiti-ate  I'an  often  be  distingnislieil.  .\ 
microscope  is  a  most  usef'd  adjunct  in  a  flotation  lalx.ratory  or  mill. 

Of.nek.Mj  ("(ixsU)Kii.\Ti(i.vs.  We  have  mentioned  at  various  placi'S 
the  relation  of  the  laboratory  tests  to  the  large-scal(>  operations  and 
now  repeat  that  in  almost  every  instanc(»  the  laboratory  results  are 
somewhat  pessimistic  as  compared  to  large-scale  work.  The  reasons 
are  made  apparent  by  the  smallness  of  the  machine  and  the  .shallower 
layer  of  froth  often  formed  under  thesi'  conditions.  Moreover,  labora- 
tory operations  seem  to  call  for  greater  amounts  of  oil,  acid,  etc., 
than  do  the  large-scale  operations. 

Oidy  one  of  the  above  machines  is  adapted  to  'roughing'  and 
'cleaning'  operations  in  a  single  test.  Present-day  practice  tends 
toward  re-tr(^atment  of  at  least  pai-t  of  the  froth  in  order  to  make 
cleaner  and  higbei'-grade  concentrates.  ronsequently,  it  nuiy  lie 
desirable  to  collect  enough  froth  from  a  series  of  tests  to  be  re-treated 
in  a  'cleaning'  test.  Of  course,  this  is  ])rovided  for  in  tlu'  Callow 
test  set,  where  oidy  'cleaned'  concentrate  is  d!seharge<l  fi-om  the 
machine.  It  is  further  found  desirable  to  \\ei>rh  and  analyzi'  some 
of  the  s\iccessive  fi-actions  of  the  froth  beinir  disehiifired  from  a 
flotatiiui  machine,  as  the  tailing  becomes  leaner,  and  determine  at 
what  point  it  may  be  desirable  to  re-treat  such  froth. 

ilany  rcpoi'ts  of  flotation  test-woik  \\'A\\  meclianical-agitalion 
machines  give  the  speed  of  the  rot.-ition  of  the  agitating-blades.  We 
have   found   that   it    was  ])ossible   1o   u'et    much   the   same   wcrk   doiic 

with   (|uite   a    \ariation   of  sjt Is.   the  only   elTcet    being   to   lengthen 

or  shorten   the   time  of  treatment       We   feel   that    the  iirii)ortance   of 
tins    matter    has    been    nnicii    ex.igi.'ci'aieii.       Sumc    means    oi     Npei-ij 
control  is  necessary  and  the  sjieed  can  be  adjusted  in  each  case  until 


TKSTINd   IIRKS   KOK    TlIK    Kl.(ir  \TI(  IN    I'KOCF.SS — II 


.■{05 


Fit;.    TTl.      TIIK   (ASK    MA(  MINK. 


tho  fl-Dtil  presents  the  proper  iippefiraiiee  ;is  tn  (leptii.  siiz,.  of  l«i!M>!i'fi. 
edlor.  ete,  Speedjiii;  tiiwiinl  the  end  of  ;i  test  in  order  to  pivo  a 
deeper  froth  with  a  faiMt  line  of  concentrate  on  the  very  top  is  often 


:!ii(; 


TIIK    ri.oT  \ri(iN    I'liDCKSS 


ii(l\  isiililc  We  rd'ominoiid  adjiistiiic;  tho  speed  in  caeli  tost  to  suit 
tiie  other  conditions,  rather  than  niniiiiiij:  a  series  of  tests  witli 
dirt'erent  sjieeds.  Only  in  the  slide  niaehine,  where  operation  of 
the  impeller  must  l)e  suspended  in  order  to  allow  froth  to  eolleet, 
is  the  speed  of  mueh  importance.  Here  we  rei-omniend  agitation  for 
a  delinite  leni;tli  of  time,  and  then  a  ])eriod  of  settling;.  The  elTeet 
of  variation  of  sjieed  during  a  definite  length  of  time  nwiy  he  a 
considerable  variation  in  tlie  amount  of  froth  eolleeted  dorins;  the 
quiet  period.  ITenee  wo  are  prejudiced  n<;ainst  tli(>  ise  of  the  slide 
niaehine  except   for  oil-test intr. 

AVhen  a  ^ood  set  of  conditions  has  been  found  for  the  flotation 
treatment  of  an  ore.  it  is  best  to  recover  the  water  from  each  test  to 
see  what  elTeet  a  closed  circuit  of  the  mill-water  will  have.  Som.' 
oil  and  chemicals  are  thus  rei'overed.  cuttiiifr  down  the  aiiiouiits 
necessary  for  operation.     In  a  carboy  or  two  of  the  water  to 

be  used  in  the  lartre  mill  s!  ■  'e  used  to  make  cei'tain  tiiat  no 
deleterious  contamination  will  ensue  from  this  source.  I'lidcr  tliese 
conditions  filtration  of  the  concentrate  and  tailinir  for  recovery  of 
the  water  is  necessary.  Such  conditions  are  provided  fiu"  in  the 
Tallow  a]>iiaratus.  above  deS(>ribed.  and  can  be  appliiMJ  easily  lo 
any  of  the  other  ii.achines. 

Oil  sainph's  for  test  purposes  can  be  obtained  from  the  various 
wood-distillinpr  companies  now  advertisinir  in  the  technical  |)ri'ss. 
from  qras  companies  and  from  petroleum-refiniiifr  companies. 

Til  altackinc  refractory  ores,  tlun*  are  a  Tinmb(>r  of  intreiiious 
thintrs  that  can  be  done  to  the  pnlp  both  in  and  out  of  the  machine. 
The  troulile  may  ho  (lii(>  to  deleterious  substances,  which  sometimes 
can  be  washeil  out.  rendered  harmless  by  boiliiis,  or  by  ai'idifyinsr. 
or  liy  makintr  alkaline  with  lime  before  entering  the  machine. 
Occasionally.  th(>  ore  will  not  work  well  under  ordinary  conditions 
but  will  yield  beautifully  after  finer  ^rindin?.  Sometimes  extra 
reagents  are  necessary,  such  as  powdered  charcoal,  modified  oils. 
argol.  soap,  calcium  sulphate,  alum,  etc,  \  rational  method  of 
devisintr  tlie  ])ropcr  tests  in  such  casi's  must  be  liased  on  some  theory 
of  tlotation.  Colloid  chemistry  is  a  branch  of  knowledgre  that  we 
believe  to  be  very  neces.sarA'  for  sucli  work,  as  it  has  facilitated  a  more 
intellijrent  control  of  our  tests  and  has  frivi'ii  wonderful  results  in 
a  niimlier  of  instances. 

Finally,  it  is  well  to  be  proditjal  in  the  amount  of  analytical  work 
connected  with  flotation  testing  in  order  to  discover  interesting 
difTerences   in    trangue-coiistituents   carried      ito    the   concentrate,    as 


TESTING  ORES  FOR  THE  FEoTATluX    PROCESS — II 


:i()7 


Well  ii.s  to  timl  the  i)est  (.'oiulitidiis  Tor  Ifaving  out  some  yaugue 
constituent  that  is  less  desirable  than  the  rest.  If  an  experimenter 
does  his  own  analytieal  work  he  can  he  expected  to  spend  three-fourths 
of  his  time  analyzing  what  has  been  done  during  the  other  fourth. 

Sununariziiig  the  most  important  points  to  be  tested  on  a  given 
ore  with  any  given  flotation  maeliine,  we  have; 

Method  of  grintling. 

Fineness  of  grinding. 

Kind  of  frothing  agent  nsed. 

Aiuount  of  frothing  agent. 

Acidity  or  alkalinity. 

Temperature. 

Necessity  of  preliminary  agitation. 

EtTeit  of  addition-agents  in  flocculating  gangne-slime. 

It  ciiii  b(>  seen  that  there  may  be  a  certain  best  combination  of 
the  above  variables  that  will  be  entirely  misised  if  a  great  many 
tests  are  not  arried  out;  hence  the  desirability  of  doing  the  testing 
in  a  small  ialmratory-macjiine  where  many  trials  can  be  made  in  a 
short  time. 

After  the  liest  conditions  have  seemingly  been  established,  they 
should  he  further  tried  in  a  larger-sized  machine  before  they  are 
incorporated  into  the  general  practice  of  a  mill.  The  test-work 
on  this  scale  need  hardly  be  described,  as,  for  the  most  part,  it 
is  a  question  of  translation  of  laboratory  results  into  large-scale 
operation. 

I  We  have  added  an  illustration  of  the  Case  machine,  evidently 
a  modified  Hoover  apparatus,  made  by  the  Denver  Fire  Clay  Co. — 
Editor.! 


308 


Tin;    KI.f)T.\TI(lV    I'UdCKSS 


MOLECULAR  FORCES  IN  FLOTATION 

Surface  Compression 

l{y  Drill, Kv  II.  N'diiuis 

(Fi(im  tlic  Miiiiiii)  mill  Siiriilifi,-  Pi,.',.s  of  Feliniary   12,  Iflldi 

At  the  iiicctinir  nt'  tlu'  local  inciiilifrsliip  of  Ww  AiiuTU'aii  Institute 
of  .Mi;iiii-r  Kii^'incns  on  i),criiili,r  14  hist  the  question  was  ask.MJ  by 
one  of  the  sjiiakers:  '-Why  docs  the  {.Teased  needle  float  on  tlic  surfa<-.' 
of  a  tuiiihhT  of  water  and  the  welted  needle  sink.'"  Did  one  or 
another  of  the  exjierts  |>re.s..nt  rise  and  say  tjjat  it  was  due  to  'surfaee 
tension'  and  then  in  a  few  well  eho.sen  words  e.\i)laiii  jnst  exaetly  what 
•surface  tension"  is.'  Xotliinj:  of  the  sort  happr-ned.  The  (pii'stion 
was  II  )t  only  not  answered,  hut  it  was  unanimously  avoided.  It  is  a 
fair  <|uestioii.  however,  and  desei'ves  an  answer. 

Tiie  fact  is  that  'surface  tension'  is  a  iiiisnonier.  Tension  is  a 
stretehintr.  whereas  the  phenoineiia,  in  (|iiestion  are  tliose  of  I'jni- 
lires,si,-.n.  In  "surface  tension.'  a  hiihhle  of  air  oi'  a  droj)  of  waler 
IS  pictureil  to  the  iiiias.'ination  as  hein>r  actually  of  the  f.u'ni  that  it 
woiil.l  have  (■/  it  weiv  contained  in  a  tiliii  like  that  of  a  soap-huhhle  or  a 
toy-halloon.  That  irrasped.  th.'  suhstarice  of  the  huhhle  or  of  the  droji  is 
iirnored  and  we  are  asked  tooccujiy  our  minds  oidy  with  the  imairinarv 
lilm.  The  reasoniiiir  appears  to  lie:  "There  miifht  he  such  a  film, 
there  must  he.  then.  is.  Otherwise,  we  ai'r  not  ahle  to  explain  it  at 
all."  In  what  follows.  T  shall  attempt  to  explain  the  plii-nomena  dis- 
cussed ill  terms  of  molecular  attraction  and  of  heat. 

If  you  will  till  a  tunihler  with  water  or  other  li(|uid  and  then  con- 
tinue eai'efuli.\-  to  pour  in  iiku-c;  instead  of  running;  over  the  side, 
there  will  he  a  lieai)inef  up  of  the  li(|uid  in  tli(-  tumhler  ami  a  roundin.i; 
of  the  surface,  the  centre  of  the  liipiid  heiiur  as  much  as  a  sixteenth 
or  even  an  eitrhtli  of  an  inch  lii{:her  than  the  rim  of  the  tumhler.  That 
is  the  plieiiomeiioii  of  your  'siirfaee  tension'  |)urc  and  iindetilcil.  The 
.same  jihenomenon  is  seen  when  mercury  is  contained  in  a  (.'la.ss  ves- 
sil,  even  when  the  ves.sel  is  only  partly  filled.  Mercury  does  not  wet 
irlass.  an  1  where  the  liquid  metal  meets  the  siilc  of  the  jrlass  vcs.sel  the 
mercury  is  convex.  "Where,  however,  the  tumhler  is  only  partly  tilled 
with  vater  the  surface  of  the  watci'  is  concave  where  it  meets  the 
inside  of  the  tumhler,  and  the  -.'lass  is  welted  hy  the  water. 

I..      *l;;i      A!  ■..".-..■.'.     ^..i..i-.. ; :      i    i      :      . :      . 

*■•      •••"       -*:;.:::::    ;:•..•:.*::!;:;     :',■;;,;■      ;;      ;',as     .^TitTeu      Tiuii      >mi  ijiee      ieil- 

sinn    is    a    force    existinfr    in    the    surface    of    a    li(|uid    that    tends 
to     draw     the     |i(|uid      into     the      f(U'm     of     a     sphere,     this     hein-.' 


MOI.KCn.AK  KoKt'KS  IX  II.UTATIo       -SIKFACK  CoMrUKSSION 


;{()!i 


till-  most  (■(impact  I'di-iii  tliat  a  ^'iveii  volume  oaii  a.s.sumc  and 
tlu"  I'oriii  ill  wliich  it  jimseiits  tiic  Ica.st  surtVe.  This  is  a 
lovely  specimen  of  tlie  lofjical  fallacy  known  as  post  hoc  (r<j„  prop- 
lir  III, I.  Ill  .surface  ttMision,  it  was  said  in  the  .Miami  case,  hccause 
I  lie  most  compact  form  that  a  "liven  volume  can  assume  and  the  form 
in  wliich  it  presents  the  least  surface  is  a  sjihere,  therefore  tlic  volume 
assumes  that  form  and  does  so  at  the  behest  of  surface  tension;  hut  as 
to  the  why  and  how,  nothini?  was  said,  nor  can  they  iie  imagined.  !t 
reads  iis  if  tliere  had  been  a  ma.ss-meetin<,'  of  the  molecules  looking 
to  'preparedncs,s.'  The  molecule  actintr  as  chairman  states  the  husiiiess 
before  the  assembled  molecules:  "Owiiii;  to  the  war  in  Kuro|)e  and  a 
hard  winter  eominjj;  on.  the  molecules  must  dei  ide  on  some  form  that 
will  he  tlii'  most  eompact  and  which  will  present  the  least  po.-sible 
surface  to  an  unsymi>athetic  world.  The  sphere  eouies  liii;hly  recom- 
mended. It  is  moved  and  seconded  therefore  that  the  molecules  form 
a  sphere.     So  ordered." 

The  calculus  i>roposition  that  two  homogeneous  spheres  attract 
each  other  as  if  their  ina.sses  were  collect(Ml  at  their  eentres  of  gravity 
is  as  true  as  anything  human  can  be.  It  is  also  true  that  in  a  single 
homogeneous  si)here.  if  acted  on  by  no  ou'side  force,  the  cohesive 
attraction  of  its  molecules  for  each  other  will  act  radially  toward  the 
(•entre  and  form  a  .sphere:  and  it  is  this  radial  attraction  and  not  an 
imaginary  film  or  a  non-existent  tension,  that  eauses  the  phenomenon, 
and  it  is  probably  some  similar  molecular  attraction  that  eauses 
mineral  flotation. 

In  James  Clerk  Maxwell's  article  on  capillary  action,  in  the  Kii- 
iiiclopiiilia  Britniniiia  ( \  1th  edition),  vol.  f).  p.  P.IR.  he  .says:  •'Plateau, 
who  made  an  elaborate  .study  of  the  ])henoineiia  of  surfa'-e  tension. 
adopted  th.e  following  method  of  getting  rid  of  the  efT(Hts  of  gravity. 
lie  formed  a  mixture  of  alcohol  and  water,  of  (he  same  density  as 
olive  oil.  and  then  introduced  a  quantity  of  oil  iufi^  the  mixture.  It 
assumes  the  form  of  a  sphere  under  the  action  of  surfa'-e  tension 
alone."  That  it  assumes  the  form  of  a  sphcn  is  granted.  Tiiat  v.n\. 
face  tension  d()cs  it  is  denied. 

The  toy-balloon  has  a  i)lace  in  a  rational  explanaticm  of  the  phe- 
nomei:a  under  discussion;  but  the  allegid  film  around  :.  droj)  of  water 
or  aror.nd  a  bubble  of  air.  or  as  the  toji  layer  of  a  liody  of  water,  like 
(he  film  of  a  toy-balloon,  has  no  existence  in  nature.  Th(>  vendor  of 
toy-balloons  has  each  one  of  his  gayly  colon  d  stock  fastr'ne.l  hy  a 
string,  which  serves  the  double  purpose  of  keeping  the  gas  in  the 
balloons  and  of  keeping  the  balloons  themselves  down  to  earth.     The 


:tl(> 


Tin;    II.dTATloN    I'UOCK; 


I'l-fi'  ends  lit'   t!ii'   stliiil,'s  ;nv   lir(iii-,'lit    to   ;i  .•oirimnri    knot.      Tliriv    is  :l 

pull  (111  each  string'  ali'n<r  the  liypotliemiso  of  a  riplit-anj;!.'  tiianu'lf ; 
this  can  he  resolved  into  a  vertical  eoinponpiit.  tending  to  make  the 
lialloon  Hoat  otT.  and  a  horizontal  component,  tcndiiijr  to  crowd  tiie 
halloons  tofTctlier. 

The  same  I  hint:  happens  in  surface  comjiression.  The  water  in  the 
tumhler  is  siihject  to  the  cohesive  attraction  of  its  molecules,  to  the 
attraction  of  <rravitation.  and  to  heat.  The  water,  if  free  from  the 
attraction  of  jiravitation.  would  tend  to  form  a  sphere,  hut  ^'ravilation 
cau.ses  it  to  conform  to  the  shai)e  of  the  coiitainint;  ves.sel.  Heat,  iiy 
tendinj,'  to  drivi'  the  molecules  ai)art.  acts  connter  to  the  attraction 
of  cohesion  and  their  e(|uilihrium  ti.\es  the  specilie  ^'ravit.v  of  the 
water,  its  hulk,  and  its  state  of  asTfrreifation— makiiifr  it  .solid,  licpiid, 
or  ga.seons  as  the  ca.se  may  he.  If  prravitation  he  neutra.ized  or  he  not 
opposed,  the  water  takes  a  spherical  f(u-m  under  tie  influence  of  co- 
hesion, as  is  .shown  in  raindrojjs.  in  Plateau's  experiment,  and  in  drops 
of  water  on  a  hot  stove,  in  conformitv  with  the  rule  of  hoiuoir,. neons 
s|ilieres. 

Let  ns  su(>i)o.se  eacli  molecule  of  ,>ater  in  the  tumhler  to  he  free 
froTH  the  attraction  of  i;ravitation  and  in  the  form  of  a  sphere,  then 
the  vertical  section  of  the  surface  layer  would  look  like  this: 


Centre  o/ Crgvitv 

FlO.    7G.      KOH(  KS   .AFFECTING   SURFACE  OF   W.\TtR. 


There  you  have  the  stock  of  toy-hallooiis  with  the  strinps  connect- 
ing each  with  a  conuuon  centre  point.  C  is  the  centre  of  gravity  of 
the  water  in  the  gla.ss.     The  lines  diverging  from  C  show  the  ilirec;- 


e  .iin.i  I  veiiicai  lines  uovvnwaru 
from  each  molecule  indicate  the  lines  of  the  force  of  gravity  and  the 
arrowhea<]s  on  the  cohesion  lines  mark  the  opposing  forces  of  heat 


MllI.KCII.AK  l-.IKCKS   l.\   Kl.(n\ri.).\— SI   HKACK  COM  I'HKSSK  IN 


:ill 


and  col.moii.  1„  th.-  triai.f,'!.'.  C  a  ,1.  f..,-  exaniplo,  tl„.  l.vpotlu.ni.s.. 
('  d  represents  llie  loti.l  for,-,.  „f  e„li,.si„n  :  r  „  ,s  its  v,Tti,.i,l  ,-,>Mip„n,Mt, 
aii,i  a  ,1  its  lu>ri/oiitiil  i',)nip„neiit.  Tii,'  r,'siiltaiit  >,(  nil  i|i,.s,.  hori- 
zontal .•oniponenls  ,/,/,  ar.  ah.  etc.,  is  a  fon'o  etr.M'tinsr  u  ,'oiMpr,,ssion  ,.f 
the  snrtm-e  of  tli,'  wiit,T.  A  p.o.l  idea  of  tl:..  stni,'tnr,.  of  sinfa,'e 
eoinpirssio.i  is  siioun  l,y  lli,.  rip,"  s.M.,l-|i,f|  „f  tl„.  ,.o,iniion  ,lan,lelion. 
•Ill,  hut  uat,'r  is  not  I'oiiipn'ssihl,'.  Tin,'  itiou-,'!!.  t,i  any  s,'nsil)le 
depri','  liy  an  ,.xteri,.r  f,)n'e  :  liut  the  int,Tior  loir,  s  at  w,,rk  in  water 
do  many  \von,l,.rful  tliin>rs.  For  instance,  they  ,'aiis,'  water  t,.  ex- 
pan, I  on  c.olinj;  an,l  to  e,>ntra,'t  ,.n  healing',  between  0 C.  an,l  4  ('., 
aii,l  all  thi'  wat,'r  i)lienonicna  of  o,'eans,  rivers,  and  rain  fall,  of 
liy,lranli,'  an, I  of  st-ain  powiTs.  ami  of  the  irresistiiile  foivc  ,,f  freez- 
in-r.  are  eaused  by  the  niohrtilar  a,'tivities  existin<:  in  a  ,lr,)p  of 
wati'i'. 

One  reason  f,)r  la.'k  of  a  elearer  un,h.rstan,linf;  of  these  phe- 
nomena is  the  faihnv  t,.  p,  PNive  the  fa,'t  that  th,'  tench-ney  to  form 
a  sphere  of  wat.-r  in  the  tiiml.h'r  is  in,'essant.  whi'ther  the  attraetion 
of  fjravitation  acts  on  the  mass  of  the  wat-^r  freely,  as  in  falling';  is 
war,]e,l  otT".  as  in  I'latean's  ,'Xi),Tiini'nt :  or  is  super-imimsed  upon  the 
attraction  of  collision,  eonipellingr  the  water  to  conform  to  the  in- 
fi'rior  shape  of  the  tumbler  and  rendering  the  ever-present  coliesion 
ini'onspieuous. 

The  action  of  water  from  the  hisrlier  decrees  of  tfmi)erature, 
thronsrh  4"  C.  to  ice,  is  shown  by  the  aecompanying  ,lrawinf;s.   A  mole- 

Fui.  77. 


VOI.r.ME    AUOVK    4°    c. 


VOI.IME    AT    4°    C. 


VOLIME    AS    ICE. 


eule  ,.f  water,  composed  of  three  atoms,  is  plausibly  ivprcsent,.,!  by  a 
triangl,'.  Two  such  moh'cules  arc  separated  a  ,M.rtain  distance  by  a 
correspondiufr  amount  of  heat,  and  tiiis  distan,v  tix,'s  tiie  volnm,>  of 
I  lie  mass  01  water,  which  increases  and  diminishes  as  the  decree  of 
heat  is  raised  or  lowered.  At  4°  the  volum..  of  water  is  at  a  minimum 
and  it  is  a  fair  inference  that  tlie  molecules  of  water  are  at  that  point 


:ilL' 


Tin:  i-i.(i'i\ii, ,.v   ri(,,cK> 


M.'iinT  t„  ..arl,  otl„T  tliMH  al  any  ,„,n,i  |{,.|„u  \  C.  ih,.  nn.l.vuhir 
l|"v,..s  ,vart  ,„  si.rl,  a  inaniirr  as  t..  .-aiis..  a  rlian-,.  in  tli,.  .vlati.ms  of 
IIk'  ni(,|..,.,ilrs  lliriMsrlvrs.  raiisuifr  tt,,,,!  t..  turn  aihl  in  tiir  Stat,-  of 
i'v-t„  assninr  tli,.  i.osilions  shown  in  ti„.  tiiini  li^'iuv,  with  a  Iouxt 
siMTil,,-  ^rravity  than  tiir  wat,..-  had  iMior.'  fivcvin-  \,,  „th,.r  funrs 
are  iK-ccssary  to  Ih-  .•aiisation  of  th,-  iihrnoMu-na  iii,ii,.at,.,l  tiian  tiiosu 
ol   cohesion  ami  in-at. 

Ilerr,  then,  is  tile  answ.'r  to  the  .piestion  askcl  at  tlie  iiir,.tini,' : 
l?y   rrasoM   (,r  the   horizontal   eoiiipoiients  of  the  attractions  of  eo- 

liesi..n   whi,.h   ,lraw   each    molecule   of   water   towanl    tli ntre   of 

^'ravity  of  ,ts  mass,  the  si  rface  of  the  water  is  .■,„„, ..vsscl.  ma.h' 
"K.re  ,i,.ns,..  a.Ml  otVers  a  resistance  to  the  nee.lle   -reater  than   the 

''■'■'-'"   "'■  "••'  ' 'Il--     That  wei-ht  is  imt  suftici.Mit   to  break  apart 

tile  surface  molecules.  Imt  only  makes  a  sli-ht  in.jentation  on  tlie 
■surface.  When  the  nee.lle  is  wettd.  eai)illary  attraction  raises  the 
comiMVsse.l  surface  over  an. I  ahove  the  n.'e.lle  wlii.'h.  no  longer 
ivstin-  upon  the  .le.iscr  surfa.-,.,  Init  in  water  not  under  surface 
compression.  ol„.ys  tlie  attraction  of  gravitation  ami  sinks. 

Attention  was  eallcl  ahove  to  the  two  cases  of  simple  compres- 
sion where  the  entire  surface  of  both  li(|uid.s.  the  water  in  th..  1, rim- 
full  tumhhr  and  the  mercury  in  the  jiartly  tilled  !.da,ss  vcss.d.  an- 
•■oiivex.   whereas  in   a   lumhler  partly  tilled   with   water,   tiie  edire  of 

the  wat.'r.   where  it    ii ts  the  u'lass  composini:  the  lumhler.  is'con- 

<'ave  and  th..  wat.-r  wets  the  -lass.  Thus  there  is  a.ld..,l  a  n.-w  force 
whi.'h  m.)dili.s  th,'  surfac  c.mipressi..ii  ,.f  th.'  wat.-r  and  .Iraws  th,' 
water  at  the  cdcre  upward  on  the  crlass.  f.irmin-  a  eon.a\  itv  tan-.-nt 
to  both  th,'  surface  of  the  watiT  an.i  the  insi.le  of  th.'  tiimbl,'r.~  Ft 
niak,>s  no  .lifTereiice  liere  and  now  what  this  force  is  call. '.I,  whether 
colu'sion  or  adhesion:  whether  it  is  the  same  molecular  attra.'ti.m 
that  exists  h(>tw,^en  th,'  moh'.'nl.s  .,f  the  water  or  wh.'th.'r  it  is  the 
coh,'si,)n  of  the  L'la.ss  actin-  at  .sensible  distanc-s.  or  n.'ith.'r.  or  both. 
Thi>  wat.'r  is  drawn  ii[i.  not  pus:;.>d  up.  and  any  .Irawiiiir  uji  is  attrac- 
tion, an.l  a.-tiiiL'  <>u  niol.'cules  i-     ;  molecidar  attra.'f ion. 

In  a  tumbl.T  L'J  inches  in  .liamct.'r  tlu'  lioriz.intal  concavitv 
atrain.st  the  -lass  seenie.l  to  b,'  about  ,',;  of  an  in.-h  wi.l.'.  perhaps  a 
litth'  more,  l.'avin-  alwmt  L'il  in.  of  .'onvexity  to  I  in.  total  coneavity,  ' 
out  of  th,'  .liam.'ter  of  I'i  in.  The  v.'rtieal  con(?avity  seemed  al.-io' 
about  ,V;  of  an  inch  alon-  the  inside  of  the  trhiss.  With  ulass  tub,  s 
of  small. 'r  .liaiiii'l.T  the  horizontal  .'oncavity  sei'med  to  remain 
about  tlie  sam.'.  but  thi>  verti.'al  .'.jncavity  in.-ri'a.se.l  as  the  diam- 
eter diminislie.l.     The  convexity  at   th.'   centr,'   of  the   surface   .le- 


MUI.KCII.AK  KOKCKS  IN  Kl.oTATlON— si  KFACi;  (n.MiMIK.- 


■ilON 


.n.} 


en.,.s..,l  with  tlK.  .lia..i,.t.r  of  th.  nyr\r  a„.l  i„  a  t„h.  of  (  ,,.  .lia.n- 
.■t.i-  tiR.  surlaee  of  the  wator  was  a,,  inNvrt,.,!  h<,lh,w  sph.r,.  whh  „o 
-•'•"Vt.Xity  at  all  and  its  h.i^Mit  ahovo  th.  h-vl  of  th-  wat.T  in  the 
tnn.hier  was  >  of  an  .n,!,.  W„l,  a  tub,,  of  ,',  in.  .i,a,n..t,.r  ,h,.  wat.T 
I'aiiic  n|>  j  incli. 

The  surlVe  compression  at  th.  ,;U,r  of  the  water  in  (he  tinnhh-r 
.s  less  than  nearer  the  eentre,  hein.^  ,,rae.ieallv  /en,,  and  olfern..^ 
HO  n.sKstance  to  the  upward  attraetio,,  npon  the  water  if  a  -i-iss 
tuhe  he  partly  immersed  in  the  water  in  the  tiimhh.r,  the  water  in 
II..'  t..he  even  if  oj.en  at  the  lower  en.l,  for.ns  a  separate  ..ohesive 
...ass,  m.iepen.lent  of  the  rest  of  the  li,p,id  with  all  the  phenomena 
01  capillarity. 

It.  has  l.een  said  above  that  the  cohesion  of  the  wat,-r  varies  in 
versely  as  the  temperature,  being  f,^reater  at  the  lower  than  at  the 
higher  temperatures,  a.id  at  the  boiliuj,  point  there  is  no  cohesion 
Witt,  the  .same  chan-es  in  temperatur,.  the  attraction  between  the 
water  and  the  jjla.ss  sides  of  the  tumbler  varies  exactlv  as  the  co- 
b.'sion  vanes,  and  there  is  every  reason  to  believe  that  the  forces 
Heyafnir  the  liquid  are  those  of  cohesion  of  the  water  and  the  .dass 
aetin^  at  sen.sible  distances.  Thes.^  ,.l.en„mena  between  the  water 
and  the  mercury  on  .me  han.l  and  glass  on  the  other  are,  of  course 
those  ot  capillarity.  They  s..em  to  fit  in  with  the  above  theorv  of 
surface  compression. 

Then  what  is  ther,.  left  of  true  surface  fusion  ?  Well  there  is  the 
soap-bubble.  I  made  some  experiments  in  this  direction  a  few  davs 
ago  with  r.O  or  60  .soap-bubbles  from  4  to  ^  inches  in  diameter  The'se 
were  burst  over  a  dark  hardwoo,]  table  about  ,%  inches  square  so  that 

tl.e  resulting  wet  .spots  on  the  surface  of  the  tabl ,uld  be  examined 

(  are  was  taken  in  every  ca.se  in  blowing  the  bubbles  to  remove  th.- 
usual  drop  of  water  at  the  south  pole  of  the  bubble,  so  that  all  the 
wet  spots  catne  from  the  wreck  of  the  disten.led  film.  After  each 
bubble  burst  the  fable  wa.s  wi,,ed  dry  for  the  next  one  Wh.n  infl-, 
t.o„  eease.l.  one  bubbl,.  .T  inches  in  diameter  shrank  an  inch  before  it 
burst :  another  shrank  from  6i  to  f,  inches.  In  both  ea.scs  tl„.  air  was 
expelled  by  a  real  surface  tension  of  the  bubble's  film  Most  of  the 
bubbles  were  blown  until  they  burst,  at  from  1  inch  to  2  feet  above 
the  table.  The  ones  at  1  inch  spread  wet  spots  in  circles  from  7  to 
U  inches  ,u  diameter.     Of  the  bubbles  that  burst  at  greater  .bstances 


from  the  table,  .at  fi  i^chrs  r.hr.-.:-  +!-. 


Mpois  c.vlcnded  to 


the  edge  of  a  circle   Ky  inches  in   diameter:  at   12  inclu-s  above    oo 
in..hes:  at  20  inches,  24  inches:  an.l  at  24  inches,  :iO  inches      ("ount- 


:tl4 


TiiK  i-i.iir  \riMN   iMicMi- 


inu'  II  i|UMrliT  circle.  iIu'Tc  xmtc  Ircnu   17")  Id  L'tin  wct  s|iii!s,  or  Tmi  \i< 
KMiu  Imp  .'iic-h  iiiililiic 

il  ujis  (■vi<lcrit  that  llic  Inrcc  tliniuiin;  liicsc  (Ircijis  iif  walci'  siH'll 
Ki'iat  (lisljiiiccs  Was  Mil!  t'lc  air  pii'ssiirc  irishlc  the  Imhiilc  Wlieu  the 
lilllililc  lilirsi  lilt'  allrarlidii  ul'  ccilicsiiPll  of  tlic  water  e..ni|)iisill>J  the 
lilin  acted  tn  re  unite  the  ilistetnleil  watery  moieeiiles  and,  as  tln' 
shortest  distance  liitweeli  two  points  oil  the  ei  rclllll  l'e|-ence  of  a  sphere 
is  iiieasiircd  on  the  •rrcal  ciicle  that  joins  them,  the  reiinitiiit;  imdeeiiles 
took  that  roiili'.  tia\elin'r  ovei-  tin'  sphei-ii^al  siirfai-i'  of  the  huhhle, 
and  uheii  a  niinilier  of  them  net  and  formed  a  drop,  all  the  nioleeiiles 
\\erc  attracted  with  a  eeitaiii  force.  'J'he  lantreiilial  components  <if 
these  cohesive  l'o|-ces.  aetilit;  ill  tile  Sllhstaiiees  of  the  spherical  tiliii 
and  at  riirlit  anu'hs  to  the  liii'  ilcs'  I'adii,  neiitrali/eil  each  other,  while 
the  eeiitrifntral  components  united  to  shoot  the  dro|)s  away  I'loiii  the 
centre  of  the  late  luilihle,  in  the  direelioii  of  the  prolongation  of  the 
ImliMes'  radii,  and  tiny  fell  in  a  wide  circle,  as  already  stated. 

Tliis  is  a  true  statement  of  the  phenol  'n  of  the  eiVect  of  surface 
tension  on  a  soap-hiihlile.  l'>y  what  stret  ,  hy  '■.  liat  torture,  of  the 
imairinat  ion  can  these  |)lieiioiiii'na  he  lirou<;ht  into  identity  or  even  the 
least  ri'Semhlancc  with  those  of  the  placid  Hoatiiifr  of  the  trrea.st'd  needle 
upon  the  compressed  siii-fare  of  the  water  in  the  tiiiiiMer  .' 

.Mr.  Charles  T  Diirell  in  an  arliidc  in  the  Miiiiiif/  anil  S(li  iilijir 
I'lusn  of  .'■';,  i-'ii  t  is.  1:11).  'iititlcd  "Why  Is  Flotation.'',  diselis,ses 
the  rising  of  a  1ml(l)le  tlirough  a  liipiiii  and  says:  '■Suiia;(  tension 
causes  the  luoleeiili's  of  the  liipiid  to  form  a  liliii  around  the  liuhhie 
and  remain  with  it  to  the  exclusion  of  like  inoleciiles  during  th<,'  time 
the  bulilile  remains  in  tln'  liquid.  To  all  intents  and  |)urposes,  this 
tilni  is  seen  to  he  the  same  as  if  it  were  a  iiu'iiiliraiio  of  some  solid.  The 
air  ill  these  Inihliles  can  no  more  come  in  eontact  with  the  li(piid 
through  which  it  is  jiassing  tlian  it  could  were  it  inside  a  toy  halloon, 
foi-  instance.  The  biitilile  may  lie  said  to  he  enclosed  in  a  'liquid  skin.' 
As  a  proof  of  his  argument  he  cites  in  a  footnote  tlie  following:  "A 
striking  experiment  to  show  tlicsc  li(|uid  films  is  as  follows:  To  a 
breaker  partly  filled  with  a  colorless  oil,  add  a  small  quantity  of  jier- 
niauganate  solution.  Blow  air  through  a  finely  drawn-out  glass  tiitie 
into  the  permanganate  solution  now  on  the  bottom  of  the  lieaker.  Air 
liiibhles  enclosed  in  the  colored  liquid  film  rise  through  the  oil  and 
break  at  tlie  surface,  liecaiise  of  the  expansive  fore<'  of  the  gas.  The 
colored  water  drops  back  through  the  oil  exactly  in  the  same  manner 
that  a  halloon,  Imrstiiig,  drops  to  tlie  earth,'' 

Witli  these  instructions  the  following  experiments  were  made:     A 


MoI.KCl'r.Mt  l(iU(i:s  IN   II.OTAIIipN 


^1  HIACi:  (  iiMl'Hl,>--/(iN 


.•!i; 


',,i\rr  (>r  Uiilrr,  liair  iiii  indi  tlm-k,  ciildi.d  clalk  Mur  uilli  a  ,|_vc  ikiI 
SipIuIiI.-   ill   ktTnM'llr.   Wa.s  |IUt    into  n  lllillhlil-  illld    llllrc   llichis  (if   Vihitr 

k<i(i.srrir  ixmri'ii  ii|i<im  it.     With  a  nirilicin.'  c|rij|i|>(r  iiaviiij;  a  rulihcr 

Kiilli  and  a  ,',.-''1    ''"''■  i'l  tl ml  nf  tjic  i,'lass  luli.  .  'miMiIcs  nl'  air  wn- 

tilown  into  till'  liliK'  wairr,  tin-  end  of  the  f,'ia.s.s  rod  resting  011  tiie 
liottoin  of  till'  tuiiihlrr.  At  lirst  tlu'  ihtssiui'  on  the  Inilli  was  made 
viTV  sTriilly,  tiif  idea  licini:  to  liavf  llir  luihlili-s  's  vMiall  as  possiMc. 
As  iiiiin\  as  2(1(1  of  tlicsc  tiny  Imlililfs  wen  lilown  and  tiicy  ros«'  to  the 
snrtair  ami  foriiicMl  a  jrroiip.  Sonii'  luiist.  some  wcii'  i'lcorporatcil 
\\itli  olhris,  and  tiiiaily,  of  course,  tiny  all  l"ii-st.  H\rry  oih'  of  tlicsi' 
2(MI  hiilihlrs  liiirst  within  a  rirdr  of  half  an  iiirli.  and  that  cirdi'  from 
tlio  limi'  of  tile  lii-si  hiililili'  until  the  last  orii\  \v,-is  not  fi'cr  from 
liiilihlis.  oiii'  touchinjj  anolhiT  and  all  forming,'  a  .siii'.'h'  compact 
Uroiip;  hut  at  no  time,  in  the  stroii','  sunli>.'ht,  was  there  the  sli^'htest 
tnico  of  hliie  in  the  circle  nor  ;in.\  where  in  the  kerosene.  The  ui)ward 
hound  III  hhles  were  pcrfceil.'  white  and  thei'e  Were  no  return  pas- 
seiifrers.  The  huhhles  had  no  films  hut  were  sim|(ly  holes  in  the  water. 
When  tlu'y  eaiiie  to  the  joint  surface  of  hliie  water  and  k- rosone, 
they  slipped  into  the  kerosene,  iiiadi'  holes  in  that,  and  hui-st  at  the 
surface  with  no  trace  of  a  tilm. 

Then,  with  f;reatcr  pressure  on  the  hulh,  larger  huhhles  were  hlown, 
and  with  them,  small  (|iiantities  of  the  hlue  water  were  forced  u|) 
into  the  kerosene.  When  tlies*?  eaiiie  separately  the  air  ros(^  to  the 
.^lirfa-.'  Mini  the  water  dropjied  hack,  hut  wln^re  they  came  to<;ether 
the  air  buoyed  the  water  up  to  the  surfaci'  where  tli(>  air  escaped  and 
the  hlue  water  sunk  through  the  keroseiii'  and  disappeared.  With 
greater  pressure  the  liubhles  hecanie  still  lar^rer,  as  did  also  the  size 
of  the  drops  of  water  forced  out  with  the  air.  Where  trapped  together 
the  larger  masses  of  air  and  hlue  water  joined  and  rose  to  the  surface, 
as  a  single  entity,  .sometimes  very  rapidly  and  sometimes  very  slowly, 
liiit  in  no  case,  whatever  the  size  of  the  constituent  parts,  was  the 
air-hiihhle  hlue.  There  were  never  any  water-films.  The  rising  com- 
bined air  and  blue-water  drops  in  the  eases  of  the  larger  bubbles  were 
in  shape  as  if  the  bubble  were  sitting  on  a  tiny  blue  feather  })ed.  In 
every  case  the  blue  water  was  below  and  the  white  bubble  above  an;I 
the  buhlile  was  pulline  the  drop  to  the  surface.  Sometimes  the  drop 
was  ton  heavy  for  the  bubble  to  float  and  both  sank  to  the  water  layer 
and  reiiiaint>(l  stationary  until  the  drop  merged  in  the  blue  water  and 
the  bublile  was  released. 

Wiien  tile  smaifer  iiui)l)les  rosi  lO  flie  surtaee  of  the  kero.sene  they  did 
not  break  as  quickly  as  in  water  but  seemed  to  strike  against   the 


:{](; 


llll.    ll.ilT.MIdX    I'iiUCKSS 


iiihlrr  siilr  (il'  ihc  .siirl'aiT  slr.iliiin  iiini  rflKiuiid  ddunuaril  mikI  uiiiviiif: 
(IV. T  t(.  Ill,'  v,\<zi>  (,f  tlic  iiiiiil.liT.  On  iifiirinir  the  jrhiss  tli.-y  si-fiiicd 
to  liM  IIS  if  iitlr.i.'tcd  ii|)uar(ily.  llkr  tlic  ])ai1  (,l  the  surfai-i'  stratum 
aroiiiiil  the  filirc  iiml'i'  cai'illary  atli'ai'tidii. 

Siiiiic  other  intfnstiiifr  plicnniii.'iiii  of  uupillarity  ucri'  notircil.  In 
the  liliii'-clrop-kiTi'srnr  fxp.'rimcnt  tlir  sidi^s  of  tlic  irlass  were  wetted 
liy  the  kerosene,  cv.-n  I.elow  ih,.  joint  siirfaee  of  tlie  Ii(|iii(}:  Imt  not- 
witlislaiidiii^'  this  faet  there  was  ()l)served  the  concavity  of  the  blue 
water  under  tlie  oih  se,'niinf,'ly  warrantin";  the  helief  tlial  the  attrac- 
tions lietween  tlie  water  and  the  ^'lass  look  i>lace  throu^rh  the  inter- 
mediate (ilm  of  oil. 

Wilh  a  liody  of  mercury  a  jzlass  tuhe  pushed  below  the  surface 
showed  a  rounded  surfai-e  of  mercury  within  the  tuhe.  with  no  I'apil- 
larity  the  ronndi'd  surface  hi'ini,'  due  solely  to  surface  eompressioii. 
With  the  tube  fioatinyr  in  the  iiienMiiw  th.'  level  of  the  outside  mercury 
was  exactly  the  same  as  the  top  of  the  rounded  contents  of  the  tuhe; 
but  when  the  tube  was  pressed  down  into  the  mercury  the  level  of  the 
iiii'reury  in  the  tube  was  lowered.  It  set'iiis  likely  that  the  indentation 
of  till'  tioatin'T  nei'dle  and  the  loverin^'  of  the  level  of  mere'.  ■•  in  the 
jrlass  tuhe  are  both  due  to  the  resistance  of  the  surfai'i'  compression 
to  the  entrance  of  foreijrn  bodies. 

Tn  the  expei'iment  of  the  blue  water,  tin'  bubbles  and  the  kerosene, 
we  come  most  unexpectedly  upon  flotation,  or  its  counterfeit.  If  it  is 
flotation,  like  the  mineral  flotation,  iiow  is  it  to  be  accounted  for?  If 
it  is  ditreivnt.  what  is  the  ditVerenee '.'  Will  an  explanation  of  il.- 
lilue-drop  kerosene  flotation  lie  that  of  mir.eral  -.lotation.  or  will  it 
help  in  that  din  ion?  There  is  surely  an  attraction  between  the  air- 
bubbli'  and  the  i.nie  ilrop.  or  \>hy  -liould  they  stick  toiretliei:'  The 
blue  drop  is  heavier  than  the  kerosene  and  the  bubble  of  air  li>;hter. 
One  pulls  uf>  and  the  otiier  pulls  ihiwn.  Why  do  they  not  sei)aratc 
unless  there  is  a  jjositive  mohcidar  attraction  between  them?  Why 
does  the  bubble,  restinir  upon  the  blue  drop,  liuoy  both  to  the  surface 
of  the  kerosene,  except  for  some  molecular  attraction  between  lilue 
di-op  ,.iid  bulibh'?  Where  this  attraction  is  manifested,  even  sliL'lilK. 
it  is  helped  by  the  static  pressure  of  the  li(|uii|  medium  in  whieii  th.' 
flotation  takes  place. 

The  trreat  unsolved  problem  in  flotation  is  the  identity  of  the 
forces  that  do  the  tloatinir.  Some  say  that  it  is  surface-  iension.  some 
eh'ctric'ity.  .ind  Miine  moh-eular  attraction  between  the  nir-butibles  and 
111''  lie  falbc  pai-tiidcs;  and  there  is  always  the  mystery  a:  to  exaetlv 
i'uf  pan  [liayeii  iiy  liii'  oil.     Tn  tiiis  article  ii  is  mti'tnlcd  to  show  that 


M(II.l:CI'l,\l{  IllKCKS  IN   rl.OTATIO.V SIHFACi;  fO.MrUK: 


-II  >\ 


:il7 


thrrc  iirc  ('(.rtuiii  iiK.ltrular  attractions  betwoeu  widely  dit^Vrfiit  siil.- 
istaiiccs  whicli  Wdiild  sri'iii  to  lie  nothing  more  or  less  than  the  foiv,.  ,,t' 
cohesion  acting  at  scnsihle  distances,  but  for  the  circiiiiistance  tliat 
such  an  interpretation  runs  counter  to  our  pre  con<'eived  opinions  as 
to  nioh'cular  attractions;  hut  tiiese  attractions  are  shown  in  this 
artii'le  to  exist  between  ghiss  and  oil.  between  glass  and  water,  dircctl.v 
and  through  an  intervening  film  of  oil.  between  glass  and  air.  and 
between  water  and  air.  The  iiiipres-sion  remains  that  a  tliorough 
examination  of  our  pre-coiiceived  opinions  may  show  that  tluy  are 
fallacious. 

There  arc  strong  reasons  for  believing  thai  the  state  of  .science 
today  is  not  uidike  ihat  of  learning  at  the  end  of  the  12th  century, 
at  the  time  of  the  great  awrkeinng.  when  the  worhl  dropped  the 
seholastieisni  of  Rom.-  ami  went  back  to  the  phikisopliy  of  ancient 
tireece.  We  have  lost  the  faculty  of  studyine:  phenomena,  we  are 
ignorant  of  the  first  jirinciples  of  logic,  and  we  have  degenerated  into 
mere  juggling  with  names. 

Proof  of  this  iMdictment  is  found  in  Vol.  XXIV  of  the  hhniirh,- 
piKlia  Britanniva,  at  page  401-2,  where  it  is  stated  that  the  pa.s.sage  of 
electricity  through  liipiids  bail  been  explained  as  a  transference  of 
a  succession  of  electric  charges  carried  by  moving  particles  of  matter 
or  'ions.'  Then  it  was  discovered  that  the  moving  particles  ',hat 
carried  the  electric  current  were  nuicli  smaller  than  the  atoms  of 
hydrogen,  and  they  were  re-named  'corpuscles.'  They  enter  into  the 
structure  of  all  matter.  The  oidy  known  properties  of  these  corpuscles 
ai'c  their  nuiss  and  their  electnc  charge  There  is  reason  to  believe 
that  the  whole  a,j)|)arent  ma.ss  is  an  effect  of  the  electric  charge.  "The 
idea  of  a  material  i)article  fiins  disapjtears  and  the  corpus<'|c  becomes 
an  i.-iolated  unit  of  electricity— an  electron."  This  is  a  typical  'sejen- 
tilic  explanation."  It  siarts  out  inventing  tli,-  word  'ion',  which  it 
inniiediately  re-christens  'corpu.scle'  and  then  'electron.'  and  the  only 
meaning  that  can  Ijc  e\lract(>d  from  the  argument  is  fluit  electricity 
is  supposed  to  he  made  up  of  imifs.  a  purely  gratuitous  assumption. 
Here  is  another  on  the  same  i)age  402:  ■•Maxwell  and  Hertz  showed 
tha'  the  velo,-ity  of  i)ropagation  of  lighf  and  idectro-magnetic  waves 
was  '  lentical  and  that  their  other  prop  rties  differed  only  in  degree. 
Thii,  light  becomes  an  eleetro-rnagnei  le  i)!ienomciion.  Hut  light  is 
started  by  .some  form  of  atomic  vibration  and  to  start  an  electro- 
magnetic wavi»  re(|nires  a  moving  electric  charge."  Here  are  tliree 
sentences  all   fallacion.s 

The  peculiar  tendency  of  the  human  mind  which  substitutes  em[ity 


318 


TIIK    Fl.dTATIOX    PiiOCKSS 


names  for  iviil  phnHwuma  ati,l  lUvu  pUys  witli  tli,.  nain.'s  ;,  tli,.  same 
that  makes  religions  (X'oplrs  wcrsliip  i,lols  instrad  .,f  tixi.K'  their 
linn.ls  „n  priMripl.-s.  It  is  easier.  A  pil-rima-..  t,.  a  shrine  where  one 
may  \v„i>i)ip  a  rafr.  a  i,on,..  (,r  a  iiank  ol'  iiair.  an  1  he  ahsolved  is  less 
troiihle  than  leadin-  an  rxempL-.ry  life.  So  that  ^^h.■„  the  .lu.stio.i 
IS  asked  ••Why  does  a  droj)  of  water  that  falls  upon  dust  take  tiie 
lorm  of  a  si)here.'-'  it  is  easier  to  say  •■()h.  surface  tension"  and  let 
n  tro  at  tiiat  than  to  think  ahout  it.  It  is  all  very  uell  t.)  sav  that  a 
snark  is  a  hoojum,  if  you  first  ddine  v(.ur  hoojum;  hut  when  v(,n 
serateh  tiie  Ih.oJuiu  an,i  lin.l  the  same  old  snark  the  pursuit  of  kn,nvl- 
ed>re  seems  in  vain. 


FLOTATION-TESTS   IN  SEPARATING  FUNNEL 

PIffect  of  Alk.m.initv. 
(From  the  Mining  and  Svivntiflr  Prrss  of  .January  S,  191(1 1 


lOl) 


iirams  of  20()-mesh  milllnads,  assaying,'  An  0.17.  Ak  2!t  5;.j 
frothed  t;  times  in  400  ee.  mill-water,  with  0.44  Ih.  S.  8.  oil^  and 
0.44  11).  eresylie  a.'id  per  ton  of  ore,  at  a  temperature  of  80^  F. 

r.ime.  II].  pel-  ton 


Test 

At 

At 

'— Concentrate-A 

ssay-^ 

—Tai 

ingAs,-ia.\ 

No. 

start. 

end. 

Gm. 

All. 

Ak. 

Au. 

As. 

1. 

0,08 

0,112 

Acid 

17.5(i2 

0,41) 

90,0 

0.12 

16.1        A 

2- 

0.01 

Neutral 

15..S59 

0.00 

110.6 

0.10 

12.4 

8. 

0.15 

15,3.".0 

0.S2 

164,(5 

0.06 

5,1 

4. 

0.25 

0.01 

A  Ik. 

i:!.470 

1.00 

192.1 

0.06 

4,1 

5. 

0.S4 

0.02 

14,20 

0.85 

184.2 

0.06 

3.8 

6. 

0.43 

0.04 

15.05 

1,00 

166,4 

O.Ofi 

4.9 

7. 

0.70 

0.12 

" 

2G.95 

0.52 

89,3 

0.03 

6,4 

8. 

1.00 

0.25 

" 

31.5b 

034 

60,3 

0.09 

12,9 

In  sei)aratory-funnel  tests,  a.ssays  of  eoneentrate  are  nnieh  lower 
than  in  phmt-practiee,     Tailinj,'-a,ssays  are  praetiealiv  the  same. 

When  frothing;  in  mill-water,  the  hest  alkalinity.'  i)oth  as  r.^iiards 
e,\1raetion  and  irrade  of  con.-entrale.  is  from  0.01  to  (1,02  Ih,  per 
ton  of  water. 


I-'LOTATIDX    I'lUNCII-LKr- 


:ili( 


FLOTATION   PRINCIPLES 

\U-  ('.   Tkukv  1)i  him.i, 
(Fioiii  the  Miiiiiiij  anil  Sncntifi,-  Pri'ss  of  1-Vliruiiry  l'.».  IDlHi 

III  attmiptiiicr  to  st:irt  u  liiscussiou  on  Hotiitioii  liy  scttiii.?  forth 
my  osmotic  hypothesis,  tlic  main  objects  were  (li  to  firmly  estalilish 
I'liiidamerital  laws  ami  (ieliiiitioiis  and  (2)  to  tiring'  out  and  classify 
new  phenomena.  Flotation  terms  have  heen  misused  and  .jumbled 
ill  the  .same  way  that  the  so-called  e.\pcrt  makes  a  mining'  report 
ridiculous  by  ;',ie  use  of  geolo<rical  terms.  Litifration  ha.s  made  the 
subject  more  confusing',  ami  it  is  still  an  iudetinite  cloud  to  most 
people.  Now  that  first  principles  and  definitions  are  beini?  afirecd 
upon,  concerted  efYort  is  startin'r  experimentation  alon;?  detiiiite 
lines  that  will  lead  to  far-reachinp;  results  instead  of  the  heretofore 
dui)lication  of  etTorts  leadinsr  to  nothincc-  Before  the  final  solution 
of  a  problem  can  lie  accomi)lished,  the  problem  must  be  stated 
properly.  It  is  therefore  quite  gratifying  to  see  that  the  discussion 
is  fulfilling  the  two  m.iin  purposes  and  that  the  flotation  ])ro))lem 
now  stands  out  more  clearly. 

A  man  can  never  learn  from  one  who  agre'«  with  him  entiridy. 
For  this  rea.son  I  was  plea.sed  to  see  exception,  (akeii  to  my  article 
'Why  Is  Flotation  ."  O.  C.  Ralston  thinks  I  used  raflier  loosely  the 
two  words  •nascent'  and  'occlusion.'  It  took  me  a  loi,<r  time  to 
realize  the  prime  es,sential  for  an  eflfeetive  froth.  This  can  only  be 
described  clearly  by  the  word  'nascent.'  It  also  required  .several 
years  of  patient  effort  to  eonviiiee  myself  that  the  whole  subject 
depends  on  gas  'occlusion.' 

Being  unable  to  learn  anything  more  in  this  country  concerning 
flotation,  some  four  years  ago  I  made  a  trip  to  Australia,  the  home 
of  flotation.  There  I  sjiw  for  the  first  time  cojiper  concentrate  won 
by  flotation.  At  tne  Lake  View  Ponsols.  in  the  Kalgoorlie  district.  I 
saw  one  of  the  old  bulk-oil  flotation  i)laiit.s. 

It  was  at  Broken  Hill,  however,  that  I  had  plenty  of  time  and 
opportunity  to  study  flotation,  ('ompanies  using  different  proces.ses 
were  naturally  ndvfrs(>  to  entertaining  a  stranger  who  might  l)e 
gathering  information  to  be  used  .-igainst  them  in  one  of  the  various 
law-suits.  As  soon  as  the  managers  or  officials  in  charge  were  assured 
that  I  was  not  there  for  that  j)urpose.  they  afl'orded  me  ample  oppor- 
tunity to  learn  everythuifr  concerning  flotati(m,  giving  me  access  to 
figures  and  data.     In  this  country,  it   is  .seldom  that  a  C(unparative 


:i20 


Tin;    FLOTATION    I'liocE.SS 


ly 


stnn,ir,.r   reeei^   .   such   cun-t.ous    tivatnient    as    was  slunv.,    , 
tlir  ri.rdial  coiniiaiiy  officials  iliere. 

At    tl„.    I'ropri,  lary    n.i,,,,    „  Ikt.    ,1,,.    Ddprat    pr.xn.ss    was    in 
.'pcninon.  ,,„  .,il  ..s  I,,.,,,.  „s..,|.  y.t  thcr.  wa.  pra,.t„.allv  tl„.  sanu. 
persistent    trot i,    as  at   otlu.-   plants  usin^  tlu-  Minerals  Separation 
process.        Ins  faet  then  eliminates  the  two  hypotheses  for  flotation 
■"i^.'"..e,l  !,y   Mr.    Ralston',   who  says  that  "The  first   hypothesis  is 
hase.l  on  son.e  aea,le,nie  work  ,lone   l,y   U.uul^s.  who  dclucea  the 
I'll'-n.cr   n.e,,uaht,es   as   appi,  .n,.    to    .   ,,.se    where   a   powder     or 
""■  P."'tHes  ol  a  e„llni,|.  is  suspended  in  a  li.p.id  to  whieh  is  added 
a  seeond   h.pnd   that    is  unniiseihle   with   the   first."     There   at    the 
1  n.pr.etar>-  .nine,  where  .".n.)   tons  p..,-  day  was  heinjr  treate.l  hv  a 
Mnde    -eelL^    no    sueh    li,,nid    was    used.      Therefore,    aeeordinfr"  to 
•Mr.   Jialston  s  hynothesis.  iVoth-tlotation  .■ould   not  tak,-  plaee      Yet 
the  reeonls  show  that  thousiuids  of  tons  of  xine  eoneentrate  has  heen 
reeovered    by    froth    where   no    oil    was   used.      I    .p.ite    a^ree    with 
Mr.  Judston  when  he  sa.vs  "It  hanlly  needs  to  he  said  that  here  we 
hnd  so„,etlnn,.  very  elose  to  the  eonditions  obtained  in  ^he  flotation 

'"■' r-   ,    "f"  ""•♦•  ""■  "''J  J-^l'"'"-e  hulk-oil  flotation  method  fulfills 

exaetly  fh.  eonditions  that  Keinders  had  in  n.ind."  By  basing  the 
whole  .sub.,e,.t  of  flotation  on  ^ra.s  oeelusion.  a.s  I  have  "done  in  ,uv 
art.ele.  ^\  hy  Is  Flotation.''  in  the  Minin,,  a,„l  Sri,,f;tir  Pn.s  o> 
September  l.S.  all  flotation  proees.ses  may  readilv  h,  exphdne,! 

On  seenifr  for  the  first  time  a  sinprle  spi^zka-sten  bein?  fed  700  lb 
"i    ".-e   per  mnnite   by   means  of  a  'push-feeder'  as  is  ,lone  at   the 
'  mpnetary,  one  .'an   but  marvel  at  the  si.nplieify  and  rapidifv  of 
aet.on  of  tins  froth-flotation  proeess.  whieh  makes  a  marketable  Vi.,e 
eoneentrate  with  hi,.h   recovery  without   re-'r-eatinfr.     As  no  oil  was 
nsed,  I  .su.nmed  up  as  follows  the  es.sential  elements:  -;,„    ,„,id    md 
l>'Mt     ,n  a,idit.on  to  ore  and  water.     There  is  nothin-  else  e.ssential 
to    th!s   treatment.      Studyi.ig   the   e(,nditions   there,    I    soon    beeamo 
••"nyuH-ed    that    the    funetion   of  the  aeid   was  not    onlv   to   produee 
I'ubbles   tor   froth-f.u-nmtion.    but    also    for  the   ereafion    of   seleetive 
aet.mK     Sniee  tl,.  solution  uas  kept  as  near  the  ,.ritieal  temperature 
<H  H)  (  .  ,,s  pos.s,bl,..  no  air  from  the  solution  eould  ai,i  in  froth.fo,.,„., 
tion  because  the  .solution   was  under  a  hydrostatie  head  and  wis  ■ni 
'mtt.Ml  at  -l!..  bottom  of  il„.  .s(,it/kMst,.n  instead  of  bv  means  of  ■,    j,-! 
above  tl„.  surface.     It  was  ea.sily  seen  that  the  fnn.^tion  of  .,;,s  w,s  for 
''•""'-'"■•'nation  and  that   the  persistence  of  the  bubbles  was  mainlv 
due  to  the  enveioiiiuir  net   of  miner;d   T,.:!rti,.lv.s.     \V!,:.(   .!,,.=-.   ,-...,.   -..',, 

'•Wliy  Ho  Minerals  Flont:"  hy  O.  C    Uiil-;tori.  .1/.  ,f  .«?.  P..  o,'t,  23.  191.', 


II.UTATIMN    rH|.\CIIM,l> 


:{2I 


fiirM'ti..!!  of  til,.  iH.at?  Tl;,.  ,-ol,l  „iv  .In.i.i.in;;  into  this  iiot  .solution 
.•i.m.M  M.inr  iiir  uitli  it  wiiiHi  tli..  ii,.:it  cxi,,.!!,.,!.  Tiiis  was  not  tl„. 
cssontial  factoi-.  Tho  licat  ckih-UM  ..noiitrli  <,f  Hi,.  o,.,.l,uk.(l  ^as  from 
111,.'  oiv  purticli.s  to  fonii  nurhn  for  Hi,,  attaclinicnt  of  nasi^ent  gas  t,i 
form  ti,itatioii  l)ulili|..s. 

Studyin,;  tiie  Kinior,.  vai'iium  proc'ss  at   tli,>  J5ritisli  Hn,iv,.n   Hill 
plant  at  a  later  dati-,   I   summcl  up  tli,.  ,ss,.ntial  ,.|(.in,.nts  tlinv  as 
follows:  va,.mun  ( t,)  lilu^rate  tlio  air-  ari,|,  oil.  and  alkali.     At  a  first 
glaiife  it  was  seen  that  here  was  an.itlur  m,.thod  of  making  Imhhh.s 
and  froth.     This  froth  wa.s  p,.rhai)s  nior,.  persistent,  as  th,.  .'uwlope 
for  the  Imhhles  seemed  tougher.     The  dit¥,.renee  was  so  slight  that  it 
is  liest  desc.rihe.l  as  that  hetween  th,-  froth  forme,!  , luring  the  early 
stage  of  the  clean-up  in  the  aei,l  or  -eutting-down'  tank  ,.f  a  ,.vani,i"e 
l)!ant  an.l  the  froth  form,.,l  during  the  lat,T  stag,..s.     It  was  natural. 
tli''n.for,..  to  a.s,sum,.  that  the  j.rineipl,.  or  ,.au.s,-  of  this  Elm,)re  pro,>ess 
of  tl,)tat.on  was  i,lenti,.al  with  that  ,.f  th,.  Delprat  at  th,.  rroi.ri,.tary. 
1  was  tol,l  ther,..  aii,l  have  li,.,.n  r,.peat,.,ily  tohl  siiU'e,  that  tn,.  oil  was 
the  ,-an,s,.  ,)f  the  seleetive  a,.tion.    I  newr  will  lieli<>ve  this,  with  all  the 
i.yiden,.,'  against  it.  alth,)ugli  on   a,.,.ount  of  a,lsorption— not   o,.,-;a. 
sion— of  ga.s's  by  th,.  ore  i)arli,.|..s.  ih,.y  ar,"  more  ,.a.sily  w,.tted  with  oil 
than   with    u;it,.r.      Th,.   n.sults  at   tli,.s..   two   iinn,.s  w,.r,.   praeti,.,!lly 
the  same.     The  gra,l,.  of  the  eoncntrate  at  the   Hritish   plant   was 
high,.r.   hy  r,.ason  of  m,.,-hanii.al   r,.tin,.ment.s,  and  not  th,.  ,litr,.renee 
m  i,ro,-,.s.s.     Th,.r,.fore  the  ,)il  cmhl  not  he  th,.  essential  ,.|em,.nt  for 
s,.l,.,.tive  aetion,  heeause  no  oil  was  use,l  at  th,'  Proprietary      The  oil 
was  an  essential  element  only  in  that  it  toughen,.,!  the  froth.     Owing 
to  .,i,.,-luini,.al   m,.ans  of  op,.ration.   the   froth   eouh!   n,.t   h,.   remove,! 
so  ,|ui,.kly  nor  could  it  he  <.arrie,l  in  such  a  deep  layer.     Then'fore 
oil  was  ad,led  t,)  tough,.n  it.     Csing  },\r.  S,.ott's  w,.r,!.s^  •■This  froth 
risf.s  and  fl,)als  much  tlie  same  as  a  h,:ar,i  woul,l"  while  the  Df.lpir. 
huhhles  "float   over,  if  we  g,.t   them  ov,.r  before  th,.y  l)r,.ak"':  and 
"if  they  ,1,1  l,r,.ak,  tlu>  mineral  .Imps  and  is  ,.aught  hy  the  huhhles 
behnv."'     Oil.  then.  ,.an  !>,.  ,.!iminat,.d  in  making  the  following  eom- 
paris,)n  I),.twe,.n  tlu'  ess..ntial  elements  of  th,.se  two  pro,.,.s.s,>s.     Aeid 
creates  the  seleetive  aetion  as  in  the  Delprat  metlux! :  lime  is  tlirn 
addcl  to  neutralize  it,  becau.se  th,.  va.-uum  rna,.liines  a.e  of  ,'ast-ir,ui. 
A,-i,l  was  foun.l  t,)  he  n,.,.,>ssary  in  the  Delpr.il  process  to  create  the 
buhhl.s.      It   ,va.s  n,.ce.s,sary  for  th,..se  bubbles  to  form  as  th,>y  "came 
into  b,.ing"  on   mineral  parli,.les  ;is  nnejei.     \:as.,.(.!!t   bn'. !•!,■.;  ,..f  -.Ar 


nValter  A,  S,^ott,  counsel  for  defendant  in  the  case  of  Minerak  Separa- 
tion !•.  Miami. 


•{22 


■rui:  I  i.(ii'vTii>\  I'f.'orFss 


•■!'•'    riinritMJ  in  tlic  sjiiii.'  \v;iv    ^,,il,.,ttL     ,  ■    , 


''•"'    •'I'vady   ;,r|,.,|    as   p.vvinuslv    ,|,.s,.n:H.,l       ri,        ,     ii      , 

:;;  I  ;,,"::,;;;r,:,:.,:: " " '"'  "'■■" ■ »'"'"  )•■ »« 

\\\\>n    I   li,..Mii  III,.  Ntiidv  ,,(•  III,.   I),.   i>.,,.  ,,. 

- y .■'-'.  I  -  a/a  J  a  • .  ;;:'r,:V  ;■  ■^-'■ 

"■'■"■  '-;■■ ,  ■'■"'■ "" "■-■'"«"' '*=««:'.."':;::::r;:;;:'' 

:^i..',f:.:'.ir:;:,,;;;;;;;ir;;z?--,.i~ 
::";;:'::";::';;:;:;,;::;;r:;;:-ir-:- »-v., 


s  <ontai„   jr..s.      It    .vquiml   a   ..nn.ful  st,.,lv  „f  f|„.  a„mritns 
at  tl„.  .\,na  ,a,nat,.,l  pbu,,  b..,-o,v  I  was  aMo  „.  i.ndor.,   „.   ' 

In-v  an,!  i„n.  was  i,   i„tn„„.„..„     This  is  hos,  .Wnl.d      '  T '  V 


>n]s:     '■Tliri)ii<jrli,>ut    this 


'    '>    "<'':'!■  ■■"i;l  as  a   ,vs„U.  osp,...ialiy  aft,^-  th,.  nili,,..    take 
"P    th,.ir    a.ih.suv    ai,--fil.Ms    aM,|     fl„at  "       Th,n-     u..,-.  -  '•}^'' 

;;:;;•;;..-..  ^^..es  Who,.  I  was  n,,.....  ins„.a.,.  h:.' .„::;;:  .,:':- 

.  .      „„,.„„,n..    ,.„ws  .,r   sta.,..n.,l    „.ia„„.la,.   .,hstn.,.,ioMs       Th 

.,...,    sh..t-,ro„    ,.„„„s    „,„i,    „...y    w,.n.    pen„.n,li,.,!h::    I: 
s       .,.        ,,,.,     ,        ,   ,^.^.,,„    „,,,,,    ..^^^,^1    ^j^_^^_^    ^.  _ 

. •     '^-^  ■^^'-  """^■*^''  ^"•^•■'*-      '1,..  s„h.j,v,in^.  of  ,h.  .lil  ,,„!(, 

^•CoBTPnlratiiis;  Oivshy  Flotation,' l,v  Theodore  r   Hn.^r     e  ,     , 

page  117,  ■    '"^"""^f  ■>■  H<'0\"r.    Spooml  cjition, 


II.OTATION     I'HINCII'I.I: 


323 


to  ,-n,„pn.sx,.,l  nu-  n,;,y  1„.  an  ,.ss,.,„inl  part  nf  ,|„.  np.n.tin,,  '•  (, 
-'"'I'HihUHlly  ,s.  and  ihis  ..i.th.,,!  is  ,,,,t,.nt,..|  l,v  Dudl.v  II  \,„,,s  • 
altlim„W,  opposod  hy  M\u,-uih  Separation  Lt.l.  wl,.,,  appii.atio,,  f,„. 
)iati'iit  was  made  in  Kntrlaiid. 

Tl„.  I),.  Hav.y  float  ^s  .a„s..,l  I,y  air.  Wl>y  is  it  not  a  iVotir 
Norns  urns  lus  sup.r-satnrate.I  li.p.id  dir-rtly  i„,o  tli.  pnlp-niass 
;'■"';'  "•"'I'  -  tonn,.d,  Ti,e  pulp  n,ass  at  th.  A.ual.an.atJi  Zino 
Idant.  super-salurated  witi,  air.  wa.s  turned  on  to  ,]„.  top  on.  of  .arl, 

srn,.,s  ol   tour  .•on..s,     Th.-ro  was  no  eha, for  fn.tl,  to  ,     n,  while 

siT.a.i.nK  ,n  a  thin  stream  over  the  siirfaee  of  a  eone      '  io,, 

however.  ,s  entirely  .litTerent  fron,  the  unstable  float  on  the  llen'rv 
J  ood  type  of  n.a-hine.  wiueh  depends  on  snrfaee  tension  entirelv 
It  .s  hest  desenhe.l  in  the  wonls  (,noted  from  He  Havav  •'Wh,.,' 
the  oontonts  of  the  reeeptaele  were  en.ptie.l  into  a  beaker  a  tiiiek 
c  eanlayer  of  'hlaek-jaek'  spran.  to  fho  snrfaee  of  the  li,,nid,  whUe 
the  white  ,-lean  -anfrue  was  j.re.-ipifated  to  the  bottom  ••■ 

t  pon  studying  several  plants  usinsr  the  Minerals  Separation 
pr<...ess,    the    lollowing    e.ssential    elements    of    flotation    were    easilv 

nvo^n.xabb.air   ,  be:,,   in   l>y  stirrers  ,o  super-saturation   ,  aeid  'oil 
rinil  Meat. 

It  is  to  he  noted  that  these  are  the  same  as  deseribed  in  the  other 
proee..ses.  'raefeally  the  only  difTerenee  is  that  the  froth  is  n.ore 
persistent,    beeause    there    is   more    slin,e    with    whieh    to    armor   the 

uW.Ies.  i  he  violent  agitation  eoa«niates  the  e.xeeedingly  fine  metallic 
pa.  t  eles  ,n  the  s,-vme  way  that  butter  forms  in  a  ,.hurn.  The.se  eoagules 
are  _f  hen  aken  up  in  the  froth  the  same  as  larger  metallie  partieles 
As  Mr.  Hoover"  states.  '"Large  quantities  of  air  are  beaten  into  the 
i  .  P  i^^  n.nnmg  the  maehine  for  a  (..-  minutes  on  water  alone,  it 
^^'11  IH.  observed  that  the  ,,„a„tity  of  air  so  beaten  into  the  pulp  is 
;;"oi-.nou.s.   t,.r  the  elean  water  will  be  milk-white."     Tins  air    .s  it 

comes  into  being  "  uses  the  mineral  partieles  as  nuelei  from  "whieh 
to  grow  into  bubbles. 

The  resume  „f  , be.se  eommereial  proees.ses  is  to  show  that  naseent 
?as  ,s  ne.es«.ry.  The  only  explanation  of  single  selective  action  for 
ail  proeesses  is  that  gas  is  held  in  th.e  solid  particles 

A  theory  that  will  not  explain  all  of  the.se  processes  is  of  no  value 
wliatever^^  Hoth  of  Mr.  Kalston's  hypotheses  depend  upon  the  use  of 

*V-  S.  Patent  No.  SG4,856,  Nov.  19.  ]90fi. 

19,5''^!:^'S'   "   ^'"'"'"'  "^    '^'"'■■"'^  «•  ""'--•"•   'r.  .f   ..  p..  .T„ly    u. 
"Tonrentratine  Ores  l).v  Flotation,'  2nrJ  edition,  page  1,-ifi. 


:524 


TIIK.    KI.nT\Tlu\-    I'HdCKss 


nil.  wliicli  is  iKii  JIM  cssriitial  clrmctit  tci  tlotiilidii,  as  was  slmuii  aliii\t'. 
Alsii  these  liy|)(jtlii'ses  assume  that  hitihh's,  existiiij,'  as  sreh  in  a  li<|uii| 
I)ui|).  eaii  tiieii  have  mineral  partiel  s  atta  hei|  to  tlieiii.  If  tliis  he  so, 
anil  it  is  not  neressary  to  <:vi)\y.  as  it,  wiM-e.  the  iiuhliles  from  the  nascent 
t;as  in  the  li(iuii|.  why  is  it  necessary  to  lieai  air  into  solution  heyoinl 
the  saturation  jwiiiit  as  is  done  in  all  fi'otli-Hotation  maehines  usinjr 
air  as  an  adjunct  except  in  the  Callow  machitu' .'  It  would  he  much 
sniipler  to  turn  in  a  stream  from  a  comiJressor  or  lilower.  If  eleetrili- 
cation  is  then  all  that  is  iiei>ded  to  produce  attachment  of  the  mineral 
pai'ticles,  surely  there  are  plenty  of  ways  tn  electrify  the  huhhles. 
Thonuis  .M.  Hains'  says,  "It  would  s<'em  easier,  therefor",  to  electrify 
a  hulihlc  than  to  keep  it  from  lieinsj;  electritied."  No;  somethinir 
nioi-e  than  elect liticat ion  is  reipiired  of  the  hulihle,  as  all  who  have 
tried  to  produce  a  tloat  in  this  manner  well  know,  James  A.  Block,' ' 
in  his  ei'ifieism  on  my  article,  say.s:  "I  cannot  see  how  the  water  in  a 
•  'allow  or-  other  pneumatic  maeliint>  can  become  greatly  super-satu- 
rated." This  is  hest  answered  In  .Mr,  ("allow'  himself:  •'The  hul.l.les 
eiimposini,'  the  froth  ai'e  <jenerate(l  under  a  hydraulic  j)ressiire  varying 
from  1.")  to  4(1  in."  It  matters  not  whether  the  wator  lie  satui'at^'d 
"with  air  at  a  i)rfssure  of  several  atmosiiheres, "  as  wa.s  done  liy 
Norris.  or  under  a  hydraulic  pressure  of  If)  iiu'hes,  lieeaus<'.  as  I 
I)ointed  out,  it  is  not  the  air  that  is  lield  dissolved,  hut  it  is  the  air 
that  comes  out,  which  is  available  for  mineral  attachment.  A 
hyjioth,  sis  lia.sod  on  nasci'nt  and  occluded  fras  explains  all  kinds  of 
flotation  as  well  as  all  tlotation  ma<'liines, 

Moi'e  tlotation  ex|ieriments  have  been  carried  oi:t  in  Australia  than 
in  an,v  other  i'ountr,v.  \o  jiublieation  of  systematic  ex])erim' 
to  learn  the  rea.sons  for  flotation  is  so  complete  as  that  in  the 
procecdinirs  of  the  IJoyal  Society  of  Victoria,  of  Kenneth  A,  Mickle." 
Ilis  expri'iments  (many  of  which  T  have  verified  in  the  laboratories 
of  the  Colorado  School  of  ]\lines  while  experimentinij:  in  the  new 
ti'stinir  jdant  there  sonu^  three  years  afjo  with  the  Ilorwood  proee.ss) 
showed  nascent  fr-is  neees.sary  and  also  that  the  particles  must 
contain  <ras,  lie  showed  by  experimiMits  thi'.t  ( 1 'i  heat  or  reduction 
of  pressure  to  liberatt  tras.  that  (2~i  freneration  of  <;as  by  means  of 
acid,  or  that    ( .!  i    super-.^aturatiori  nf  solutions  with   <ras.   will  catise 


"The  Electrical  Theor.v  of  Flotation,'  li.v  Ttionuis  M.  Bains.  ,Ir..  M.  d-  S.  P.. 
Nov.  27,  1915,  page  S24. 


"'r>iOu.-?  0(1   i-'iuiai  iuii."  i(>    .1.  M.  (\i\'ii.iw  .  M.  a    .<.   p.,   Tfec,  -*,    ir»i;i,  liu,<t'  >•  -. 
»Vol.  XXIII  and  XXIV  (N.  3.),  Part  2,  1911.      Abstracted  in  Enp.  .f  Min. 
Jour.,  iia.cc  .!07,  Aur.  12,  1911  (vol.  92),  and  jiagc  71,  .lul.v  13,  1912  (vol,  94). 


l'I.UI'\TliiN    I'UINClI'l.l 


:{25 


minerals  tn  tloat  nr  tend  t'>  Hnat  wilhdUl  tlic  aid  nf  oil.  lie  sliuwcd 
till'  clTi'ct  (pf  frasi's  iifiduilrd  liy  niiticfais  to  lie  il  i  llic  pai'lii'lrs  are 
iKit  wholly  Wetted  when  iniiiierseel  in  water;  ( li  -  the  j)articles  tend 
to  float  when  sprinkled  on  water:  ( .'!  i  the  parti<des  when  immersed 
eolleet  hiihliU's  as  tlio  solution  is  hijiti'd  or  exposed  to  vaeuuin  and 
float  or  tend  to  float:  and  (4i  the  jiaftieh's  in  gas-saturated  solutions 
eolleet  the  hiihhles  evolved.  He  says,  '•In  my  earlier  j)a|)er,  it  was 
shown  that  mineral  particles  ahsorh  ^'ases  to  an  extrnt  not  previously 
sus|)eefed  and  that  they  retain  the  s;as  adsorittions  with  such 
persistency  that  they  could  ni'itlier  he  easily  separated  hy  meehanieal 
means  n(U'  nun'li  atVceted  hy  trravity  and  jias  expansion."  He 
also  says.  ■'In  ])re\i()iis  itwesti'jatiiiiis.  T  found  that  carhon  dioxide 
was  ohtained  I'rom  all  sulphides  liy  the  aid  of  heat  and  exhaustion 
in   the  presenc(>  of  water.     It    is  prohahle  that    the   i.'as   lihii   imu    he 

ex|ianded  for  I'einoval  in  appi iahle  ({uantities  only  in  the  presence 

ol'  water  and   that   exhaustion   in   the  dry  state  does  not    remo\e  all 

the  jrji.s  present." 

With  a  view  to  further  invcslifratinir  the  jras  held  hy  solids,  he 
condMetcd   the    followinij  experiments: 

1.  ('upper  aihi  silver  foil  were  (deaiicd  with  sodium  hydrate 
and  distilled  water  and  dried.  These  and  uncleancd  iiieees  wi're 
treated  in  a  \ac\niii)-flask.  Ki'\\  huhhles  l"ormed  on  cleaned  foil  with 
distilled  and  air-free  distilled  water,  hut  more  on  the  uncleancd. 
All  foil  floated  in  tap-water. 

2.  Six  steel  needles  Were  cleaned  in  tiie  same  way  as  the  I'oil 
and  allowed  to  stand  one  half-hour  in  alcohol  and  then  drieil  in  a 
desiccator.  They  would  not  float  on  di.stilled  water  until  if  had 
been  ex|)osed  for  .sonic  time  to  the  air.  Another  set  of  needles 
and  iron  wii'e  were  similarly  cleaned,  hut  would  not  float  until 
allowed  to  stand  in  a  desiccator  for  two  days.  The  sjiinc  results 
were  ohtained   with   sulphides  cdcaned   with   sidphuric  acid. 

"These  (>xperiiiients  show  that  jierfiM'tly  cleaned  needles  and 
iron  wire  will  float  on  the  siirfai>e  mi<ler  the  t'ollowin<r  conditions: 
(ai  if  the  water  is  allowecl  fo  stand  for  some  time  in  contaef  with 
air;  (]i'  if  the  7ie(>dles  and  wire  are  allowed  to  7-einaiii  exposed  to 
the  air  for  sufficient   time."' 

'i.  ('leaned  and  uncleancd  j)ieees  of  iron  wire,  on  heiiifr  immersed 
in  a  saturated  solution  of  carhon  dioxide,  showed  the  following 
results:  (a^l  clean  jtieees  collected  very  few  huhhles,  while  (lil 
unclean  }>ieces  were  covered   with  a   frost  of  huhhles, 

I   have  coritlriued   these  experiments,   therefore    I   aiu   j>ositive   of 


:j2 


I'Mi:    l-l.nT  \TliiN     rUdCK: 


till-  incnMv.-iiirss  ..r  Mr.  Kicliii Ill's  stalfiiirril.  '•If  ycii  |,l,i,r  nii 
onliiiaiy  n.rdlr.  say.  a  lao'  ihmmIIc  suilalilr  Tnr  iim>  with  Xo.  ,s(i  ilm.ail. 
""  ''!'■  siirlarr  ,,f  a  licwl  i.f  uali-r,  it  ^illks  at  ..nee  !■.  tlu'  iMittcnii. 
Ill  .ilir,|i,.||,T  to  III,,  law  (if  trravity.  If.  linucViT,  ynu  pass  ||i,.  urrdii' 
tlirciifrii  ydiir  liair.  s.i  that  it  lircduus  trivascd,  it  will  tloat  mi  the 
wat.T."'  '  Tills  is  the  saiiif  nM  false  as.siiiiiiptii>ii  that  ml  is  a  lu'ccssity 
iiistrail  111'  an  a'd  In  tlnlalimi. 

Swiiiliiiiiir    and    K'nd.irf  '    say.    '-.X    way    of    d.'iiionstratiiii:    tli- 

pivvriirr    of    trasrolis    .  ■  I  ]  \ ,  •  |o|  irs    is    to    sift     solllc    powdiTcd    slllislancf 

\\liirii  easily  sinks,  sudi  as  sand  or  frrrous  siilphidrs,  ii|>on  tlif 
snrfa.c  of  hot  water.  piv\ioiisly  fiv.'d  from  iras  hy  lioilintr.  HiiMilcs 
of  j:as  iisr  from  the  siirfaei.  of  solid  part  ii^lcs. "'  --It  spmns  niMTssarv 
that  tho  LMs  slimild  lir  prodm-rd  al  tli,  ..rfarc  of  th,-  paniidcs 
tlirms.Kcs."  I'll,,  air  lilm  always  plays  ..n  important  part;  an, I 
il  III''  III''  is  ihoi'oiiL'hly  wash,., I  ,ir  lioil,.il  in  watrr  to  remove  tlic 
air  lilm.  ii  ,.aiiii,p|   h,.  roiicni  ral,.,|  with  ai-i,l." 

Ther,.  an.  many  otli,.)-  r,.f,.ivii,-,.s  all  sliowintr  tin'  same  tiiiiij,': 
llial  till,  iiiimral  parthhs  to  he  tioatrd  must  I'oiitain  iras  so  as  to 
ai'l  as  niii'lei  for  the  iras  as  il  ■•,-oiii,.s  into  Iwiiij.'"  from  the  iiipiid. 
Tli,.|vl'oiv.  in  my  former  aiiiel,.,  1  ,li,l  not  pres.'iit  this  ,.vid,.|iee  to 
prov,.  ni.v  slatem,.nt.  whii-li  se,.m..i|  a  s,.lf-,>vid,Mit  fart  in  vii'W  cd'  tin' 
pi'esi'lil    kno«l,',|i_'e   of    Ih,.    siilije,'!. 

.Mi,-kl,'  rolleeteil  j.M.s,.s  from  eoneent rat,'  mail,'  from  Broken  Hill 
iiialerial  some  of  which  i;as  i-onlaiiied  : 


I  1  I 


N  . 
O  . 
CO, 


{)  . 

CO. 


.   2 
.Ifi 


It  is  seen  that  these  fja.ses  obey  IT,.nry's  law.  ea,-li  ,'\istiiiLr 
iiidopi'ndent  of  the  otli.'rs  and  not  ilisplaeinfr  the  othiTs  as 
Mr.  lihiek'-'  says  iiniioiiliteiily  \\,)ul,l  be  the  ease.  An  analysis  of 
a  samp],'   I'rom  the   Ilorwood   proi'i.s,s  fjavo: 


N 
O    . 

ro 


.    1 
4 


These  ttire,'  sami)les  of  pras  beeaiiie  ilisenprai-'eil  from  three  samiiles 


"■Wliat  Is  Flotation?'  li.v  T.  A.  Rickard.  M.  d  S.  P..  Sept.  11.  l!il.-|.  iia,£,'e  :;s4. 
■    r-;:;:r:-  :-,:;;:   :;;■;;;?;■   mr    ;  arauaV   oOiiti.>,    Dec.   12,   1905,  "u.v   .J.   swinimrne 
and  G.  Rudorf.     Abstracted  in  Kntj.  if  Min    Jour.,  Feb.  10,  1906. 
i-.Ianies  A.  Hlook.  If.  if  .s.  />..  Ott.  'Mt.  1;)1.-,.  page  li')!*. 


Ki.nr  \i'i(i\    riiiM  ii'i.i;s  327 

nf  iMiicciitriifr  uhirli  u,r.'  mIIuu  nl  to  stand.  A  Itrrujinl  a  vaciiuni 
.■i|i|>lir(|  to  No  1  saMipir  1  70  >,'iii.  sulpiiiilr  t;avf  a  fiirtlicr  amount 
ot'   1  '  I'c.  Iras  aiialv/iiii.' : 

^     27% 

O    H.l 

<■<>:     58.8 

On  liiisinir  III'-  li'iri|>iTatni-i'  lo  the  lioilintr  point  and  sulijcrtinij 
this  sain])!!'  to  \ai-nniii,  tliiiT  was  tlii-n  t-'ivrn  otf  >.'J  vr.  of  tjas, 
vliM-h    was    t'onnd    to   I..'    pfai-ti.-ally    all   caflion    dioxide 

i':-oni  tlif  Xo.  li  sanipjr  h,.  oliiainfij  Is.:,  ,■,..  irjis  of  wliicli 
practically  all   uas  CO..     On  sulijcciintr  miihraN  to  reduced  pressure 

•■Hid    heal,   lie   I'oiiiid   that    I oiild   olitain    iiioiv  ir,is   I'roiu   ealeite  and 

i|ilarl/.  This  uas  mostly  CO..  lie  proved  in  all  these  ea.se.s  that 
the  ( '<  > ,  ol  it  allied  was  not  tVom  the  decomposition  ot'  eariionales.  This 
shows  that  mini  lals  in  t'l'iieral  ocrln.le  lms.  allhouirh  .Mr.  Iialston' 
says  that  '■i^'ood  ea.ses  ot'  o. •elusion  ha\e  heen  I'oiind  thii.s  I'ar  only 
in  amorphous  siilistanees."  .Mr.  IJIoek  is  ipiite  riu'lit  when  lie  says 
"lh;il  it  Would  he  hherated  with  sul'tieient  rapiility  to  float  the 
particles  does  not  seem  prolialilc.""' ■  .\|so  .Mr.  IJalston'  is  correct 
in  sayiu!.'  "How   the  ti^'ht  ly  held  t;as  eoiihi  he  liherati^il   t'.ist   enouirli 

to  com|)are  with   the  exceedinijly  short  time  wlii.-h  it   takes  to  ai m- 

plish  flotation  of  a  sulphide  particle  is  ditlicult  to  explain  piiysically. " 
F  simply  stated  that  •'if  this  jras  lie  expelled  from  tliem.  wiieii  they 
are  in  a  liipiid.  at  a  time  when  the  ^ras  is  expelled  from  the  liquid, 
they  heeom.'  the  nuclei  for  the  t'ormation  of  "ra.s  liutihles."  On  tiip 
other  hand,  if  Imlihles  are  not  formed  from  iia.scent  iras  of  the 
liijiiid  in  contact  with  the  mineral  iiartici,.  there  lan  he  no  adhesiiui 
hecause  tile  liiihliles  art'  Surrounded  hy  liquid  lilm.s;  or.  if  the 
particles  contain  no  occluded  !,'a.s.  there  can  he  no  adhesion  liecause 
the  p,articles  are  siiri-oiinded  hy  litiuid  films. 

That  these  two  words  'nascent'  and  'ocelusion'  were  olijected  to 
shows  the  neces,sity  of  extreme  care  in  the  ehoie(>  of  terms,  and  I 
am  criad  that  .Mr.  Ralston  hroucht  ui>  this  point.  'Nascent'  is 
detined  in  Wehster's  Xew  International  distionary  (."irdi,  Ittl'),  as 
follows:  "Binnor  horn:  eomiiior  into  existence:  tieg^innintj  to  frrow ; 
coiiniiencin}^:.  or  in  proees.s  of,  development."  The  Century  dietionary, 
")tli  edition.  1011.  ffives  praetieally  the  same  definition  as  follows: 
'"Hefrinninp  to  exi.st  or  to  crrow;  eommeneitifj  development;  cominfj 
into  iiein?;  incipient."  The  following  usage  is  given:  '"Wiping 
away  the  naseent  moisture  from  my  brow:  Barhain.  'Ingokisby 
Legends'."      Available   gas   of  any   kind    for   flotation    must   "eome 


;J2« 


llir.    1  l,ciT  \l|n\    riiiiCKSS 


Ititn  Imiiil'"  ill  lliis  u;i\,  Mr.  r.;iins'  caci  r,.iil  ly  .lisiTilirs  tlii>.  ;is 
t'dlliius:  "ir  |inuilirr,|  i:,il,n;i  err.  with  a  liiiirsloni'  LMiit;\li\  he 
dropped  into  imrc  water,  most  "(  tlie  powdiT  uill  iiniiirdialcly  sink 
t(,  tllr  linlldlll.  As  the  air  cin-losrd  liy  tln'  parlii-lrs  is  . April.,! 
pradiially.  nnr  sirs  tln'  t'dniiatidii  of  ■arinori'il'  liiiMilis.  soini'  of 
wliirh  may  last  fur  da\  s.  II, ic  is  Hutatioii  wiliioiil  oil  or  ari.j.  If 
nilrir  arid  lie  addod,  tlic  ;:as  huMiIrs  I'urnir.l  liy  tlir  artion  nf  tin- 
jirid  Mil  Ihc  <.'aii'_'Ur  "ill  larry  \i|i  paili'-N's  of  tralciia  "'  I  liav<> 
jijarod  '.  iin'h  piir(s  of  c|iiarl^  iraliiia,  and  otlicT  iiiiiirrals  in  i\ 
li.'akiT  lillril  witli  water  satnratid  \vitli  air  at  ainiosplirri.'  pivsMiiT. 
Tlif  purposr  was  to  watrh  tlic  fMriiialion  of  tlii'  lniliMrs.  More  sinall 
liiililil.s  formed  nil  the  iihtallie  minerals  when  heat  uas  apjiliecl. 
The  hiiKhles  fni-med  on  all  minerals  apparently  in  the  same  way 
that  iiMiislnre  fnrms  mi  one'  hrow.  I  wish  to  ih'serihe  this.  TlieiM^ 
is  (iiilv  one  sint-de  werd  in  the  F,nj;lisli  laiiL'iiaLre  that  ean  he  used 
I,,  ,1,,  it  -misei'iit.'  This  is  n.it  "the  dissolved  (ras  that  ean  lie 
liheratid.""  hill    it    is  the  dis,siilved   ..'as  at   the  instant   of  lih.'rati.m. 

U.^ranlinu'  o.'.dnsimi.  Mr.  I\alst..n  has  li.en  kin. I  I'lioiiL'h  to  m.'ii- 
tieii  three  ways  hy  wli.'h  -.'ases  .'an  h.'  held  in  seli.ls.  ami  I  sli..ul.l 
hav.'    ns.-.l    imnv    eaiv    in    the    .dioi.'e    of    the.se    terms.      I    us.mI    tlii> 

w.M'.l  ■ hnh.r  as  a  i.'eneral  term  to  denote  either  siirfi adsorption 

or  s.ilid  s..liitioii.  As  .Mr.  K'aUt.ni  says,  ■■this  is  a  term  tin-  m.aiiins.' 
(d'  whi.di  has  heeii  nnieli  disinite.l."  Tryinu'  to  sh.iw  that  the  >;as 
in    the    mineral    oheys    the   sam.-    l;iws  as    the    iras    in    th.-    li.piid.   as 

]. roved    hy    .Miid<le.    I    spoke    of    the    ^'as    heillir    dissolveil    ill    tlli'    solid 

Jill, I  thus  leil  u|)  to  the  i.rm  ■o.-.|usion."  liaviiiL'  in  miml  the 
f.ill.iwini.':  ■'The  aiii.'iint  ><(  ^'as  whieh  dis.snlves  in  a  ^'iv.ii  .|iiantity 
of  water  is  ],roiiortional  to  the  pressur.  .  and  from  this  exp.'rimental 
iTsiilt.  Van't  llotV  showed  matlieinalieally  hy  the  iirin.'iple  of  thermo- 
dyiiniiiies  that,  when  in  solution,  this  same  f:as  miist  ex.rt  an  osmotic 
pressur.' ";"  and  that  '  ■  Sidistan.-.'s  .lissDlve.l  hy  soli.ls  lia\.'  an  .ismotic 
])ressiire  as  shown  hy  \'airt  HofT.  so  we  ean  sjx'ak  of  s.ili.l  dilu- 
tions" :''■  also  that  "the  frrenter  the  ])ressiire  t.i  whieh  the  jras  is 
suhjeeti'il.   th.'    Iar<rer   the   ipiantity   wlii.'li    will    he    a.lsorh.'d   hy   the 

soli.l.""' 

N'is.'ositv    is    anotler    w..r.l    tliat    has    he.'ii    ineorre.'tly    use.l    in 


i-i'Tlie  Elpetriciil  Tlionry  of  I'loiation,'  l.y  Tlidiiias  M.  liaiii!;.  .1/.  .1  N.  P.. 
Nov.   27,   l!il.'.   liau'p  S21. 

M-riio  Re.-,. lit  lie\eln!ini.  nt  of  I'livsiral  Srieiire,'  by  W.  C.  I)am|iier 
Whethani.  iiage  IIH.  2n(i  edition.  IIHM. 

i.-'/e?r   P)n)S.   Ch<m.:   lS!tO,   .",.   7.Z-1. 

I'l'Elements  of  Pliysiral  f'lieniistry.'  liy  Harry  C.  .Tones,  i;hi2.  iiaue  2r.7. 


•i.or  viMiN   iMU.\rii'i.B 


:!:;:) 


tlllo.     ilS 


Damiiier 


.■ohllirtlull      Willi     tlol.ltidl..         Ml        Kic|<,'l|-(l'  '     ill     Ills     iirl'rlr,     '  Willi!      i.S 

l-'lii|atiiiii  .' '  stiilrs:  "Tlir  idiiiliiiiiil  inn  nj'  |i,u  tiiiMnii  aiMJ  liiu'li 
Ms.i.Miv   fiialili's  a   liiihlilc  d''  iiiis.   risii,^;  llii'i>Uj.'li   the   lh|iii<l,   Id  lili 

llli-  silflarf  tillll  111'  !lic  lii|lli<l.  wllji-ll  the  t.'iisioii  (iT  llir  lilllililf  tillil 
is  iiiil  sli-niit,'  iiioiii.'li  141  I  nak,  sn  lli.'  Imlilil,-  ciKliirrs'" ;  ami  cites 
■  \  Tr\t,  lionk  (iT  Ihc  I'l  iiiciplcs  cil'  I'livsirs."  1 1>  AH'mmI  Daiiiii.'H. 
1:  11  Alsii  Mr.  Ki'kaiii  slal^s:  "1'iiit  \\alcT  lias  triTat  siirfai'c 
tciisiiiM.  it  also  has  no  .sii|)iTlicial  viscnsily.  " 

N'lscdsily    as   kiidwii    Inclas'    is   an    intiicly    (iitVi'i-ciil    iifdpcrl y   of 
iiialtiT    frdiii    that    wliicli    DaiiiiiiH    in    Iss.".    cdiil'iisril    with    siirfan' 

Irllsidii. 

I'l'i-hajis  till-  hrsi  cji-linitidn  nf  visi'osity  is  hy  Hai-ry  ('.  .Idiics.'' 
as  I'dllows:  'We  iii'tMJ  simply  iiicniidn  In  ic  llic  udrks  nl'  I'disi'iiillc. 
I'aL'liani  and  liallclli.  Sldltf,  ( iartfiiiiiiislcT,  and  'rfaiiln'"'  •  •  • 
"Tlif  iiidiiiiiiii'nlal  wcii'ls  dt'  'riidi-pr  iV:  luidurr  miTit  iihut  carrl'iil 
atl'iiiidii."  •  »  •  ••'I'liry  in-dvc  cdin-liisivcly.  ulial  has  lucn  hinlcil 
al  iMldri',  that  •  •  •  viscdsity  may  he  'aki'ii  as  thi'  sum  (jf  the 
altrai-tivc  fdiccs  in  jilay  lictwrcii  tin'  iiidli'ciilrs ;  •  •  •  I|  is,  thcri'- 
rnic,  iiiadi'  cvidi'iit  that  viscdsiiv  di-  inlir-iiidlrriilai-  attrai'tion  is 
in  fiality  a  |)rdpirty  df  tlie  atimis  dt'  wliidi  tlif  mnli-ciiics  arc 
cdiiipdsrd."  This  ■supcrtirial  vis<'()sit\- '  is  well  explained  in  the 
Hin  i/i  lnji,i,li(i  llriliniiiini,'^  as  I'nlldws:  "The  \aryin<r  nt'  cdiitaiiii- 
n.'ilidii  td  which  a  water  surface  is  siihjcet  ari'  the  ciiiiscs  dl'  many 
ciii-idiis  |)liendiiieiia.  Amon-r  thcso  is  the  "siiix-rlicial  viwosity'  of 
Plateau. "  •  •  •  ■•I'lateiUl  attriliutes  these  ditTereiiees  to  a  sjiecial 
cpiality  of  the  liipiids  iiamiMl  iiy  him  ■superficial  viscosity.'  It  has 
tiecii  proved,  hdwever,  that  the  question  is  (iiie  iif  contaminatii 
and  that  a  water  surfaci>  iiiiiy  he  [ireparcd  so  as  to  heliave  in  the 
same  iiiaiiiior  as  alcohol."  ..Ir.  Rickard,  in  his  second  article,  pafje 
.")17.  Miiiiiifi  ami  Sciiiitific  I'nss,  Octolicr  2.  IDlf).  says:  •'To  make 
liiilihles.  the  surface  tension  of  water  in  the  flotation-cell  nnist  he 
decreased  by  a  contaminant  and  at  the- same  time  the  viscosity 
of  the  li(|uid  must  he  st  reiisitliened. ' "  As  shown  alxive,  it  is  not 
the  visiMisity  hut  the  fjeneral  surface  tension  efTect  tliat  nnist  l)e 
strcntrtlieiied.  As  I  pointed  out,  a  sojiihle  or  i)artly  soluble  oil  will 
decrease  the  surface  tension  of  water  hecausc  it  dilutes  the  water. 
which  lia.s  the  fireater  surface  tension.  15y  I'cason  of  this  catise 
alone,    the    tendency    to    float    is    liecreased    and    the    huhhles    luiist 


'•Coiuliictivity  and  Viscosity  in  :\Iixed  Solvents,'  Carnoyie  Iiislitiite,  I'li!)!!- 
ratieu  Xo.  SO,  1907,  pace  19. 

I'Uth  edition,  under   TapiMary  Action." 


:!:!(i 


Till-:    KLOTATION    I'KOfKSS 


inoru  easily,  rsi.ijr  n  \,,liitil(-  oil  in  a  M.  8.  macliinc.  I  luive  had 
the  imhhles  hurst  so  violently  that  thr  ceineMt  floor  was  hlackeiie.l 
M-ith  zinc  suli)lii(le  at  a  distaiu'e  of  several  feet  from  the  machine. 
At  the  same  time  I  was  makiiif?  a  very  clean  zinc  eoii.rntrate  from 
Leadville  mi.xed  sulphides  after  a  Ilorwood  roast.  As  no  other 
contaminant  was  used,  this  was  only  made  possihle  hy  havinj;  the 
tnineral  particles  well  oiled  with  the  thinnest  possilile  film  to  aid 
cohesion  in  armoring;  the  huhhles  well  with  the  zinc  sulphide  particler.. 
lu  this  case  the  surface  tension  was  still  further  reduced  hy  the 
sulphuric-acid  electrolyte. 

Most  oils,  however,  aid  modem  flotation  in  three  ways,  as  I  tried 
to  point  out  in  my  former  article,  hy  (1)  deerea.sinf?  the  force 
of  adhesion  of  water  for  mineral  particles  hy  fornung  films  around 
them,  (2)  increasing  the  cohesive  force  of  the  mineral  particles  for 
each  other  to  aid  in  the  formavion  of  a  network  of  mineral  particles 
around  Ihc  liuhhles  to  toughen  them,  and  (3)  toughening  the  huhhles 
hy  forming  films  of  oil  around  "'  huhhles  in  addition  to  those  of 
the  water.  'Touglien'  is  not  a  good  word  wherehy  to  express  the 
meaning  Mr.  Ralston  explains  this  -ery  well  and  at  length  on 
page  624.  Mining  and  Scioitifie  Pre.t.t  of  Octoher  23,  IHlo,  under 
his  inter-facial  tension  hypothesis.  He  clpims,  however,  "It  is 
doul)tful  if  the  air  hul)l)les  could  he  completely  mciitled  hy  oil." 
Tliis  is  contrary  to  the  experience  of  others.  The  colors  on  the 
huhhles  indicate  that  they  are  mantled."  This  shows  that  Mr. 
Callow  is  right  when  ho  says  "Tlie  huhl)le-maiitles  in  a  flotation- 
machine  are  nndoulitedly  composed  of  oil,  or  oil  emulsion."'"  The 
sum  of  these  tension  effects  causes  persistent  huhhles.  even  though 
the  surface  tension  of  tlie  water  has  heen  reduced.  TheEe 
iindonhfedly  arc  extremely  thin  films,  at  least  approaching  one 
molecule  in   thickness. 

Therefore  molecular  forces  must  he  taken  into  account  in  dealing 
with  them:  as  :\rr.  Kalston  says.  "The  underlying  cans*'  of  the 
tensions  and  of  electrie  charges  is  the  same  thing — some  strange 
molecular,  atomic  or  other  force  manifested  in  'adhesion.'  'cohesion,' 
or  even  'gravitation,'  if  you  plea.se."  Tn  dealing  with  *hcse  inter- 
facial  tensions,  the  drop-weight  method  cited  hv  Mi  roghill"'  for 
determining  surface  tension  is  of  no  value  to  flotation. 

The  inler-farial  hy,(othesis  of  Jfr.  Ralston  explains  very  well 
indeed   the  jjcrsistency  <if  Imhhlc,;.  Inif  T  am  not  so  ea.sily  satisfied 


'"'Notes  on  Flot.ition.'  liy  .T.  M.  Callow,  ^f.  .(  ,V.  P.,  Dec.  4.  191.').  pace  .S,'>4. 
•-"'Surface  Tension.'  In-  Will  II.  CoKhill.  M.  a  K.  p.,  Oct.  9.  19i:    page  .543. 


FLOTATII  )N-    I'KIXCII'LKS 


331 


as  IS  Mr.  Bl„ck,''  who  says,  -T.  J.  Hoover,  for  instance,  in  his 
book,  'Concentrating  Ores  l.y  Flotation,'  presents  a  consistent 
theory."  Mr.  Hoover  (2n(l  edition,  page  72)  savs:  "There  has 
been  no  satisfaetoiy  theory  yet  propoinuled  as  to  whv  acid  does 
promote  the  preferential  a.lhesion  of  water  to  gangnc  particles." 
Kven  the  lat.^  electrical  theorj-  fails  to  answer  all  the  questions 
asked  by  Mr.  Hoover,  on  page  ]00  of  his  book.  I  answered  tlie 
above  question  in  my  article  by  showing  that  an  acid  or  anv  electro- 
lyte creates  osmotic  pressure,  by  tr>'ing  to  enter  the  solid  particles 
ot  which  their  surfaces  act  as  sentums.  If  this  pressurr  be  sufficient 
to  drive  most  of  the  gas  out  from  the  gangue  particles,  the  metalli.- 
particles  can  be  floated,  for  the  reason  that  there  is  still  left  suffiei.^nt 
gas  in  them  to  ecome  nuclei  for  bubble  formation  bv  the  nascent 
gas  of  the  liquid. 

As  shown  by  Mickle's  experiments,  mentioned  above,  there  is 
more  gas  in  sulphides  than  in  other  minerals  and  it  is  held  more 
persistently  in  the  sulphides.  Thus  a  selective  flotation  is  created. 
I  have  confirmed  these  tests. 

P:veryone  who  has  e.Kperiraented  with  flotation  has  seen  how 
too  much  acid  will  'kill'  the  float.  That  is,  ihe  greater  osmotic 
pressure  drives  f:e  air  from  the  metallic  particles  as  well  as  from 
the  gangue  particles. 

This  etfeet  is  not  to  be  confu.sed  with  that  caused  bv  substances 
such  as  tannin  or  saponin  mentioned  by  Mr.  Callow'"  as  colloidal 
impurities  or  volatile  oils  and  the  like,  which  destrov  bubbles  by 
reducing  the  surface  tension  to  the  extent  that  the  gas  pressure 
from  within  breaks  or  even  explodes  them.  This  weakening  of  the 
surface  tension  by  a  colloid  is  an  entirely  ditferent  phenomenon  from 
that  shown  when  the  osmotic  pressure  is  increased  by  a  crvstalloid 

"The  crystalloids  when  dissolved  in  water  change  in"  a  marked 
degree  its  properties;  for  example,  they  diminish  the  vapor  pn'ssure 
lower  the  freezing  point,  and  reduce  the  b.iiling  point."-' 

And  as  Dr.  Lupke-  states,  the  four  laws  in  speaking  of  dilute 
solutions,  are  "  Kquimolecular  .solution:;  of  anv  substances,  prr,,ared 
l)y  using  equal  w,.ights  of  the  same  s<3lvent,  exhibit  equal  osmoti,. 
l)ressure.  equal  relative  depres.sions  of  vaponr-pres.su re,  equal  risings 
of  boiling  point,  and  equal  lowerngs  of  freezing  point." 


-i-Text  Book  of  Phvsios.'  by  J.  H.  Povnting  &  ,1   .1 


Tlioiniison,  3rd  edition. 


==The  Elements  of  Eleetro-Chemistrv.'  by  Robert  Lupke,  2nd  edition,  1903 
eaRe  119. 


:]:V2 


THE    FLOTATION    TKOCESS 


III  iiiaiiitaiiiiiif?  that  osmotic  pivssure  of  an  cli-ctrolyte  is  tlio 
oaiise  of  Sfl(Mtivc  tlota  i  n,  it  is  well  to  look  into  the  motive  power 
ol'  osmosis.  Kahlcnht-rir-'  states  it  ''lies  in  the  speeifie  attractions 
or  atHiiitiis  hetweeii  the  li(|iii(is  used  and  also  lietween  the  latter 
and  the  septum  employed.  These  atKnities  have  also  at  times  heen 
termed  the  potential  energy  of  solution,  etc.;  they  are,  to  my  mind, 
«ssentially  the  same  as  what  is  termed  'chemical  affinity'."  Or, 
as  F,  II.  Carrisou-'  put  Tauhe's  theory:  "The  drivinj^  force  i!i 
osmosis  is  a  sui)erficial  (or  inter-facial)  pre.s.sure  ohtaine.l  hy  snb- 
tractinsr  the  surface  tension  of  one  fluid  from  the  tension  of  the 
fluid  into  which  it  ditf'nses."  Or  asjaiti  as  Van't  Ilotl"  and  his 
followers  contend  'Tlie  molecules  of  a  dissolved  substance  e.\ert  the 
same  pressure  against  a  semi-permeahle  membrane,  during  osmotic 
l)roces.ses,  as  they  would  e.x(  rt  against  the  walls  of  an  ordinary  vessel 
were  they  in  the  ga.seous  state  at  the  same  temperature  and  the  same 
concentration.""  Since  these  authorities  do  not  agree  on  the  motive 
force  of  o.sinosi.s,  investigation  must  rest  for  want  of  further  data. 

However,  all  tiieories  of  flotation,  be  they  eh'ctrical  or  otherwise, 
must  come  to  ostnosis  for  their  solution.  This  is  not  to  question 
the  fact  shown  by  electrolysis  that  every  atom  of  matter  is  capable 
of  uniting  with  a  deKnite  quantity  of  electricity.  Nor  is  it  to  question 
that  corpuscles  (later  termed  electrons  by  Dr.  Stoney  i  do  not  revolve 
around  atoms  wliicli  are  thousands  of  times  larger.  Hut  it  is  to 
question  any  hypotliesis  that  does  not  take  into  account  the  fact 
that  particles  will  not  float  when  all  the  gas  is  driven  from  them. 
Osmotic  pressure  can  fn.-  particles  of  their  occludeil  gas.  Whether 
osmosis  is  caused  by  electricity  or  whetlier  a  etirrent  of  electricity 
is  caused  by  osmosis  has  no  bearing  on  flotation.  However,  in 
l>assing,  it  may  be  of  interest  to  mention  that  Dr.  Robert  Liipke, 
in  his  liook.  'Elements  of  Electro-Chemistry'  devotes  Part  III  to 
"The  Osmotic  Theory  of  the  Current  of  walvanic  Cells.' 

As  mentioned  above,  extreme  dilution  of  the  electrolyte  ;itTects 
the  osmotic  pressure  and  selective  flotation.  AVith  complete  dis.socia- 
tion.  as  Arrhenius  has  shown,  the  ionized  molecules  are  free  to 
obey  electric  forces.  It  may  be  freely  granted  that  air  driven  from 
a  particle  by  osmosis  may  eflfecf  a  change  in  the  'contact-(ilm' 
mentioned  by  .Mr.  Callow  and  leave  the  particle  negatively  charsred. 
so  that  it   \\(iul(l  sink  as  descrilK-d  by  him.     Also  it    is  grant'd  that 


=  <'A    Note   on    Taiilie's   Tlieory   of   Osmosis   and    Altiartion    Prrssnrc,'   l)y 
F.  H.  GaiTison.  Ann.v  Meiilral  Museum,  Srir»rc,  vol.  ^2,  10li».  puKc  2><:!. 


ir.()TATI()X    PHINCIIT.KS 


.{33 


the    mineral    particles   are    all    either    negatively    or   positively    ( ?) 
••harged.     Assuming    the    eleetrie    eliarges.    there    th.'ii    enters    the 
important  qiiesti.iii  mentione.l  by  Mr.  Callow  in  siating  his  tlieory 
that  •■the  partieles  possessing  them  will  migrate  when  plaeeci  in  au 
electric  field."     There  is  no  question  but  that  with  an  eleetrie  tield, 
flotation  can  be  produced  in  such  a  manner  iis  described  liy  Hotiie 
Scliwenn  in  his  ■Khvtro-Osiiiotic  Pnx-ess'---  as  follows:    "ily  inven- 
tion   consists   of   adding   electrolytes    to    the    liquids   containing    the 
substancc-s  to  be  separated,  the  nature  of  the  electrolyte  depending 
ujwii    ,he   character  of   the   substance.      If   the   latter  is  of  sur],   a 
character  that  they  would  be  deposited  by  the  electric  current  on 
th,.  cathode,  idectrolyte  of  acid  character  are  employed;  and  if  the 
suljstances  would   be   deposited  on   the   anode,   elect'rolvtes  of   basic 
character  are  used."     Speaking  of  finely-divided  substances,  some- 
times indifferent  to  the  a.'tion  of  an  electric  current,  he  continues: 
"I  have  found  that  such  substances  can  be  made  electricallv  active 
by  causing  them  to  absorb    [here  ustnl  as  defined  by  Mr.   Ralston] 
colloidal   substances  of  a  .strong  electro-i)ositive   or  "electro-negative 
character."    Of  the  recent  electrical  theories  advanced,  none  explains 
lu'W  this  imix.rtant  electrical  field,  mentioned  as  necs-sjiry  by  Mr. 
Callcw,  IS  created  by  any  flotation  niachine.     Mr.  Hlock-"  shows  this 
on  a  clay  machine. 

After   selective   flotation   is   created    by   osmosis,    it    matters   not 
whether   the   particles   be   spoken    of   as   being   held    together   or   to 
the  bubbles  by  electric  charges  or  by  cohesion  and  adhesion  in  the 
way  I  mentioned.     Sir  Oliver  Lodge,='  after  saying  that  "the  force 
ot   chemical  affinity  iias  long  been  known  to  be  electrical"  goes  on 
to    say    that    "there    is   another   kind    ,.f   adhesion    or   cohesion    of 
molecules,  not  chemical,  but  what  is  called  molecular.     This  occurs 
lietween  atoii.s  not  possessing  ionic  or  e.xtra  charges,  but  each  quite 
neutral,  consisting  of  paired-off  groups  of  electrons."     However  great 
this   attraction    may   be.    the    mineral   particles   will   not    adhere   to 
bubbles  already   formed,   as  was  sliown   abov;   but,   using  them  as 
nuclei,  the  nascent  gas  will  form  into  bubbl,  s  to  float  them.     Such 
gas  formation  is  excellently  described  by  Duhem^'  as  follows:   "From 
this,  a  bubble  of  vapor  will  luv^-r  be  iormed  in  a  region  where  the 


"U.  S.  Patent  No.  99.'?,SS8. 
2«'Notes    on    Flotation.'      Discussion. 


Bulletin    A.    I.    M.    E.,    Dec, 


1915, 


"Chapter   If,,   'Nature   of  Cohesion.'    in   hook    'Electrons,'   bv   Sir  Oliver 
Lodge,  P^inclp.^l  ot  the  University  of  Birmingham. 

■-'s'Thermodynamics  and  Chemistry.'  by  P.  Uuhem,  1903,  Art   275   page  366 


334 


TIIK    FLOTATION    ruOCESS 


li(iui(l  is  continuous;  in  fart,  if  sudi  a  hulitiii-  could  licgin  to  form, 
its  radius  would  be  at  first  intii'licl.'-  small— less  than  the  limiting 
radius  of  which  we  have  sjMikcn  ;  whence,  instead  of  contiiming  to 
Kn>\v,  it  would  collai)sr."  On  the  next  pajre  be  continues:  '-These 
considerations  do  not  api)ly  merely  to  boiling;  they  completely 
explain  a  trreat  number  of  phenomena." 

The  eleetrically-charged  mineral  parti(des  may  aid  in  bubble 
formation  allhoujrh  they  cannot  effect  attachment  of  mineral  particles 
to  l)idibles  already  formed.  Regardiner  this.  Dr.  Thompson=^  says 
that  ••the  char-red  partitdes  act  as  nuchi  aroun.l  which  suudl  droi)s 
of  water  coiiden.se.  when  the  parti-des  are  .surrounded  by  damp  air 
cooled  below  the  .saturation  point."  "Experiments  were  made  with 
air,  hydrogen,  and  carbonic  acid  and  it  was  found  that  the  ions 
had  th.-  same  eharge  in  all  the  ga.ses."  ■  Iso,  "Thus  by  suitably 
choosing  *he  super-saturation,  we  can  get  the  cloud  deposited  on 
the  negative  ions  alone  so  that  each  drop  in  tne  (doud  is  negatively 
charged."  Elcctrieity  may  manifest  it.self  in  various  way.s,  but 
flotation  cannot  take  j)lace  witliout  na.scent  or  occluded  gas. 

=o'The  Atomic  Structure  of  Electricit.v,'  Chapter  4,  'Electricit.v  and  Matter.' 
By  .T.  J.  Thompson.     Lectures  at  Yale,  May,  1903. 


TilK  ELECTKO-STATICS  OF  FLOTATIu.V 


335 


THE   ELECTRO-STATICS   OF   FLOTATION 

By  F.  A.  Fahrenwali) 
(Piom  the  Mining  and  Scientific  Press  of  March  11,  1916) 

The  .levlopnient  of  every  nv^^■  n.etallurgieal  method  is  a.co.n- 
panie.l  by  a  host  of  eontradietory  statements  and  widely  ditferiiig 
"Punons,  but  it  is  only  by  the  eliniinatio.i  and  correlation  of  parts  of 
recorded  observations  that  a  particular  process  approaches  a  state 
ot  perfection.  Tiie  theory  of  flotation  has  called  forth  a  number  of 
articles,  eaen  writer  applying  a  ditferent  hypothesis  in  explaining  the 
puzzling  phenomena  accompanying  the  process. 

Of  the  various  hypothes..s  thus  far  advanced  only  two  are  based  on 
pnnciples  of  snfKciently  apparent  soundness  to  warrant  serim.s  con- 
sideration. 

The  first  of  these  inv.,lves  the  physical  surface  phenomena  that 
may  produce  an  inter-facial  tension.  This  ha.s.  until  recentlv  been 
accredited  with  more  importance  than  all  tl,c  other  explanations 
combined.     The  second  is  called  the  electrioal  theory. 

The  part  that  surface  phenomena  may  i)lay  in  linking  tiie  particles 
of  ore  to  the  bubble-carriers  is  ably  outMned  by  0.  C.  Ralston,  whose- 
trea  inenf  of  this  phiise  of  the  question  includes  reference  to  about  all 
of  the  theoo'  that  ha^  so  far  been  found  applicable  to  flotation. 
VV 1  hout  doubt  a  proper  application  of  the  laws  of  physical  chemistry 
W.11  disclose  fundamental  principles  upon  which  this'process  may  be 
based,,  and  it  may  be  in  the  field  of  colloidal  chemistry  that  most  in- 
tormation  is  to  be  gained. 

With  reganl  to  the  electrical  theory,  however,  fher«  has  been 
applied  a  number  of  laws  of  electro-statics  that,  from  the  general 
nature  of  conditions  under  which  flotation  is  carried  out,  would  seem 
to  be  inoperative. 

This  hypothesis  has  been  tolerated  by  Mr.  Ralston.^  if  is  strondv 
advocated  by  J.  M.  Callow\  while  Thos.  M.  Rnins.  Jr  ^  ..x.-Iudcs  all 
other  theories.     These  three  references  .'ontain  I  he  gist  of  all  arAi 
nienfs  advan.v  d  in  support  of  this  liypothesis.  and  the  In.st  of  then, 

Of  t'hrLor""""'  ''""'"'■ '" '  '■  "■'  ^"''^'-  ''■  ''''■ «- "'-  -.0 17.. 


•T,  p^,  r!r  '■'''•'^-  s^«-'"^p'^s<' 231  Of  this  book. 

-The  Eler.nral  Theory  Of  Flotation.-     .U.  .(.S'.  P.,  November  '7    nr,    an,, 
December  11.  1915.    See  also  pa^es  225  and  25S  of  th  .  boo) 


;};{() 


Tin:    FLOTATION    THOCKSS 


HaiM.n,t...s  an.l  .Irlinitely  I'ormulaf.s  th,.  ,„.cr.vsMry  miui.vnont.s  lor 
Hotatin,,  l,y  el-.tric-al  means.  It  is  my  ohject  to  attempt  an  analysis  of 
the  vanows  arfrui.ients  a.lvaneed  i„  swj.port  <,f  li,e  eleetrieal  tluM.rv 
ami  as  the  only  diflVrenec  between  this  an.l  any  otlu-r  theorv  li.-s  in  th," 
piienomena  that  cause  the  bond  betwe..n  tlie  Hotative  mineVal  an.l  tie 
linbble-earner.  it  is  understood  that  only  this  i)hase  of  tiie  pn.eess  is 
under  disc-ussion.  Jt  is  neeossary.  howev.r,  in  order  to  arriv  at 
praetieal  eonelusions,  that  this  qu.^stion  be  eonsi.lered  under  condi- 
tions Mnidar  to  those  encountered  in  practice. 

Before  proceeding  to  a  discussion  of  the  electrical  theory  of 
flotation  It  will  be  necessary  to  point  (.ut  briefly  a  few  of  the  facts  of 
electro-statics  upon  wliich  it  is  l)ased. 

A.  The  production  of  electricity  by  friction  is  a  common  phenom- 
enon; almost  any  two  bodies  become  electrified  if  they  are  rui)])ed 
together.  In  the  case  of  .several  substances,  considerable  force  is  tlien 
necessary  in  order  to  separate  them.  ..tfractioi,  or  repulsion  also 
occurs  when  an  elect riHed  body  is  brought  near  bodies  that  have  been 
sulgected  to  friction  and  if  thes«?  are  light  enough  (as  bits  of  pitch 
feathers,  wood,  paper,  etc.)  they  may  l)e  lifted.  Bodies  mav  also  become 
electrified  by  coming  in  contact  with  other  bodies  that  already  carry  a 
charge.  In  this  ease  the  first  body  receives  electricitv  of  the  same 
sign  from  the  charged  body  and  is  then  repelled. 

B.  Bodies  that  when  electrified  at  one  point  are  immediatelv 
electrified  all  over  arc  called  good  conductors;  tho.se  over  wliicli  the 
charge  diffuses  slowly  are  poor  conductors.  All  metals,  manv  metallic 
ores,  graphite,  ordinary  undistilled  water,  and  arpieous  solutions  nf 
salts  are  good  conductors. 

C.  If  a  piece  of  metal,  or  other  conducting  material  held  in  the 
hand  is  rubl)ed  against  a  non-condu<'tor— say,  a  piece  of  dry  flannel- 
only  the  non-conductor  appears  afterward  to  be  electrified.  The 
reason  is  that  the  electrification  produced  on  the  metal  spreads  over 
the  hand,  arm,  and  body  of  the  e.xperimenter  to  the  floor  and  walls  of 
the  room.  If,  however,  the  conductor  be  insulated,  the  degree  of  its 
electrification  cannot  be  increased  or  decreased. 

D.  By  wliatever  process  a  body  is  electrified  there  is  always  an 
equal  amount  of  electricity  of  the  opposite  sign,  which  may  reside 
upon  the  walls  of  the  -nclosing  room  or  upon  some  otlier  surface  in- 
sulated from  the  conductor.  Bodies  carrying  opposite  charges,  when 
brought  in  contact  or  connected  b.v  .1  conHneff.r    hanr.m.-  .?-:=...! 1 

itralized. 


than  the  other  the  system  takes  on  the  sign  of  the  excess  charge 


lire 


THE    KI.KCTKO-STATICS   OF    FLOTATION 


337 


K.  It'  those  liodics  iirc  stronply  plcctritiod.  discliarfrc  can  take  place 
tlirnueh  an  apprccial.lc  thickness  of  non-oondiictiiit?  material,  such  as 
air,  (lil.  or  glass.  This  discharge  is  facilitated  by  the  presence  of  sharp 
projections  npon  either  hody. 

V.  (a)  The  space  between  two  charged  bodies  is  filled  with  lines 
of  force  that  tend  to  move  a  contained  body  in  the  direction  of  the 
local  lines  of  force  leading  to  the  surface  carrying  the  opposite  sign. 

(b)  These  lines  of  force  do  not  penetrate  the  surface  of  the  con- 
ductors forming  its  boundaries  and  a  hollow  conductor  is  electritied 
on  its  outside  or  inside  surface  only,  depending  upon  whether  the 
oi)posite  charge  resides  upon  one  contained  without  tiie  sphere  or 
upon  one  contained  within  and  insulated  from  the  shell.  In  the 
latter  case  the  entire  field  is  contained  within  the  inner  surface  of 
the  sphere,  and  in  the  former  ease  there  is  no  charge  witliin  the  h(>llow 
I'onductor. 

G.  The  force  e.xerted  between  two  small  charged  bodies  is  given  in 

the  equation  V=  ^,  in  whicli  q  and  q'  are  the  charges  in  electro- 
static units  carried  by  each  of  the  two  bodies,  and  d  is  the  distance 
between  their  centres  of  charge.-'  If  the  bodies  are  separated  by  a 
iiu'dium  other  than  air  a  factor  K.  known  as  its  dielectric  coefKicient, 

must  be  used,  and  the  equation  becomes  F  =rr  -  .  -^ 

k       d- 

ir.  ]\Iatter  itself  is  not  acted  upon  by  an  electric  force,  which  acts 
oidy  between  different  (luantities  of  electricity.  When  a  conductor 
is  introduced  into  an  electric  field  it  represents  a  gap  or  an  interrup- 
tion of  the  lines  of  force,  resulting  in  an  electrification  of  its  surfaces 
only,  that  part  i)ecoming  positive  which  is  presented  toward  the  nega- 
tive hounilary  of  the  field  and  the  reverse.  In  other  words,  the  original 
field  is  divided  into  two.  This  s;imc  effect  is  produced  in  the  case  of 
a  poor  conductor  but  to  an  exceedingly  sniii'l  degree.  This  explains 
the  attraction  of  small  bodies  by  another  that  lias  been  electrified  by 
trictioii.  in  which  case  electrification  by  influence  precedes  attraction, 
and  what  is  really  observed  is  attraction  between  opposite  electric 
charges. 

Before   considering   these   fundamental   laws   of  electro-statics   in 

'•onnccfion   with   an   exi)laiiation  of  flotation  phenomena,   it   mav   be 
..    11  .  ■  1       ,    ,   ,.       .  ...  _ 

luiuliiiims  under  wiiicii  diitereiit  plias<'S 


>f  this  process  take  plai 


•■■The  force  exerted  hy  a  cliargcd  spliere  ai 


ts  as  if  originated  at  tlie  centre. 


;{;38 


■IJIK    1'I,(JT.\TI(|.\    l'IiOC'KS8 


_      Of  first  i.nportam'e  is  tl.e  fact  that  all  openttion.s  are  earri..d  out 

u  abk.  that,  alter  any  f^nnding  pnH...s,s  has  1,...,  applied  in  maehines 
such  as  arc  co,>un..nly  us,.!,  the  indunlual  positively  char.-cd  particles 
of  ore  s  ould  not  have  co.ao  in  contact  with  negatively  char,,'  h„dies 
ami  ^^,h  conduct,n^'  parts  of  ,M-in,lin,^  and  nnxin,^  machinery,  even 
't  od  has  heen  added  in  a  prclindnary  sta^^^  The  ore  parth'les  arc 
-'.  uctoz.,  the  oil  is  a  non-conductor,  the  huhhh  s  are  filled  „i,|,  non- 

;;;;;;;';:;;;;''-  ""•  *""'  "'^  f^''"f^>"^  f-  -n.,.osed  of  non-eonducti.,g 

Tl.ese  conditions  hcinj;  ^ranted,  tiic  next  step  will  he  to  apply  the 

aws  ol  electro.stati,.s  to  criteria  for  flntative  conditions  accniin-  to 

he  eleeincal   thcry.   as  su.nn.ari/ed   hy  Mr.   JJains.      TIh.s,.  inch.de 

ti:e  man,  nha.s  of  Mr.  Callow-s  article  and  of  the  th.'ory  in  ^^.neral 

so  that  a  d,s,-uss,on  of  these  in  onier  uill  aj.ply  to  the  Various  „ther 

firticles  advanciii",'  a  siiiiihir  hypothesis. 

J.  ••Ores  containing   valuable   n.in,.rais  or  metals   that    are   -ood 

conductors  are  tl nly  ones  that  are  suitable  fnr  flotation  " 

This  se<.ms  in  -encral  to  be  true,  but  the  ratio  of  flolative  tendency 
to  conductivity  „f  the  dilVcrent  .uv  eonstiluents  is  nothin-  like  a 
constant.  For  .n.stance.  the  conductivity  „f  pdena  is  to  the  conductiv- 
ity -d  chalcocte  as  .'JS:  1.  Their  ri.tative  tendeucies  hardly  bear  this 
I'atio. 

I"  'nliie  (opposition  to  this  supposed  requirement  I  found  that 
suiall  luces  of  ,l.amond  attract  a  irreasC^  or  nil  coatiny  and  attach  to 
liulibles  (piiti>  as  readily  as  does  galena. 

2.  '-To  buoy  these  conductors,  it  is  n.  cessary  to  supply  enough 
Pleetnlicd  bubbles  from  below  to  float  particles  of  the  conductors  that 
are   attractd;   hence  the  smaller  the   bubble.   th(>   better   the   result 
the  amount  of  <rns  beino  the  same." 

A  hulible  within  a  solution  of  various  salts  and  acids  presents  a 
snndar  condition  to  that  of  the  air-space  uithin  a  h.dlow  eon.luctiu- 
•sphere  It  ,s  known  r.s..e  F  (h)  above)  in  this  case  that  in  order  to 
have  a  charf,'e  upon  this  inner  .surface  it  is  necessary  that  an  opposite 
ebarjre  be  numitauied  within  and  insulated  from  it.  In  the  ca.se  of 
the  bubble  there  is  nothing  in.side  to  carry  the  charge.  In  case  this 
space  cairii'd  water-vapor  m-  ioniz.d  gases,  a  charge  could  he  present 
hut  If  wotdd  b,.  dissipated  quickly  by  ditl^^usion  of  these  charged  par- 
ticles and  resulting  contact  with  the  water-surf.-iep. 

J^tli^ sphere  did  contain  charged  gases  and  was  lined  with  oil, 

"This  fart  is  utilized   in  tlie  recovery  of  diamonds  at  Kinibcrley. 


THE   ELECTUO-yTATIC'S   OF    FLOTATION 


339 


there  woiilil  lie  present  tlie  ronditioii  of  tlie  hollow  eon<liictiii£r  s|)hcres, 
I  F  (l>i  I  with  eiielo.seil  ehargeil  eoinliietor  insiihiteil  from  it.  and  carry- 
ing an  opposite  i-liarp'.  The  eliar^es  would  he  equal  and  the  amount 
^.'(iverned  hy  the  eharfii'  on  the  inside  sphere  These  eharf^es  heinf? 
halanccd,  the  huhhle  system  eould  have  no  influence  upon  a  hody — 
charf,'ed  or  not — witiiout  the  outer  sphere,  such  as  a  particle  <if  traleiia 
suspended  in  the  water  at  a  distance.  There  can  lie  no  attract i. in 
throu<,'h  the  interveiiiii<j  conductor,  as  lines  of  force  will  not  penetrate 
a  eonductiiiLT  surface. 

It  apjxars  evident  then  tliat,  first,  unless  a  huhhle  contains  charu'ed 
hodies  (ionized  <xi\.<i.  water-vapor,  or  solid)  within  its  houndin<,'  si)hero 
it  can  carry  no  ehar<,'e ;  second,  that  uides.s  it  is  lined  with  a  dielectric 
the  ehar<,'e  will  he  rapidly  dissipated;  and,  third,  even  thou'jh  a 
charfje  is  present  and  insulated  from  the  outer  conducting'  sphere  it 
can  have  no  attraction  for  any  hody  or  charge  without  the  outer 
s])herc.  through  a  thickness  of  solution. 

:{.  "Some  ilielectric  fluid  is  necessary  to  cover  the  conductor  or  the 
hubhle,  to  prevent  the  dissipation  of  the  electrie  charge.  The  tiiinner 
the  film  of  dielectric  and  the  greater  its  dielectric  str.  ugtli  the 
greater  the  attractive  force  and  the  more  permanent  will  he  the  froth." 

The  hu)il)le.  hoth  insulated  and  otherwis«\  hixs  been  considered. 
The  particle  of  ore,  unless  insulated,  will  he  inunediately  discharged 
hy  coming  in  contact  with  a  grouiuled  conductor— the  .solution.  It  is 
immaterial  whether  the  opposite  charge  is  carried  hy  the  water  or  hy 
some  other  surface,  the  effect  will  he  the  same.  Assume,  however, 
that  the  ore  particle  is  charged,  and  insulated.  Again  we  have  the 
case  of  nne  charged  eonchictor  ithe  ore  i  being  enclosed  within 
another  (the  surrounding  water  solution)  giving  a  system  which 
is  neutral  with  regard  to  any  other  charge  or  system  without  the 
outer   sphere. 

I'nder  conditions  eleetro-.statically  ideal  these  forces  may  be 
pictured  as  in  Fig.  70.*  Both  bodies  are  charged  and  insulated,  and 
.suspended  in  an  intervening  conducting  medium.  The  systems  ore- 
oil-water,  and  ga-s-oil-water.  are  without  effect  upon  each  other. 

In  case  the  gas  is  generated  from  the  ore  the  ^article  eould  not 
be  insulated  unless  liy  .some  phenomenon  not  understood  at  present. 
If  the  gas  is  air  pa.ssed  mechanically  into  the  pulp  it  would  be  forced 
into  contact  with  ore  particles,  in  which  case  the  charges  carried  by 
each  would  have  its  eftect  upon  liie  otiier.     That  a  mass  of  air  con- 


•See  page  .S42. 


:{4() 


TIIK    Kr.nT\Tr()\    I'KOCKSS 


taininp  .'hartr..,!  va|..,r  or  ^.,us..s  ,.„wM  I,.,  insulat,.!  \,.f„r,-  .■o„mi.'  in 
contact  with  t\w  conducting  dilution  is  not  misontiMc 

Assuming,  however,  that  l.oth  ho.lics  arc  char-d.  so  tl,,-,t  Mic 
secon.i  part  of  Xo.  :{  ,ahovc,  regarding  ,],c  thi,.kncss  of  insula- 
tion may  now  l,c  consider..,!.  It  has  licon  ,,rovc<l  that  the  force 
exert.-.i  l,y  a  .■iia.red  sphere  a,.|s  as  if  it  was  coMcenirated  at  the 
'•.'litre.  Hcanng  this  in  mind  it  is  evidmt  that  in  tl,e  ca.se  of  particles 
-'I  the  s,/.e  witi,  which  flotation  deals,  a  separation  of  thci,-  surfaces 
hy  one  micron  or  one  millimetre  will  pnuluce  little  practical  ,litV..rence 
111  the  force  exerted  hetween  tiiem. 

4.  '-Some  material  must  he  add.^l  to  the  water  to  increase  its 
'•-'ii.im't.vity.  to  ohtain  a  ..lean  .■..n..entrat.. ;  aci.ls  in  .small  am..unts 
ar..  now  iis...l." 

This  fa.-tor  has  h..en  ....nsi.i..r...l  iin.I..r  divisi.,„s  2  an.l  ;!  The 
w.u-kuifr  solution  is  a  con.luct.,r.  parts  of  whi..h  ar..  int(  rposc.l  h..tw..en 
the  varmus  char-..,!  particN.s.  theirhy  l.n.akiu!:  all  li„..s  of  fon-e 
between  them. 

In  any  att..mpt  t..  .I..termin..  ..xperimentallv  wh..th,.r  or  not 
electrostatic  for....s  play  any  ....nsideral.le  part  in  hol.lin-  the  l.ul.l.le 
aJi.l  parli..I..s  of  ore  t.)}r..ther  it  is  rather  .littieult  to  .s.'leet  tests  which 
will  frive  n.sults  of  value.  If  these  for..es  a.-t  to  the  exclusion  of  all 
oth.-rs  It  is  ..vi.l..„t  that  they  would  be  repr-sent...!  l.v  ..harg.^s  of  easily 
nicasurahl..  matrn.lii.l,..  For  ..xampl...  I  hav..  ,s..parate.l  par1i..l,.s  of 
palena.  (uncoat...!  with  oih  that  hav..  he..n  ..arrie.l  to  the  to,,  of  an 
aei.l  solution,  w.i^'idn.  GO  mg,  (.'.L'  m-  in  wat..r).  To  hol.l  a  parti,.le 
of  this  siz..  to  the  surfa.-e  of  a  bubbl..  rcpiiivs  r.O.!)  ,lvn..s-^..all  it  ".O 
■  n  r.mn.l  nnmb..rs.  Th..  .liam..ter  ..f  this  parti.-le  is  al,..ut  2  milli. 
m..tre.s.  Tim  bubble  r...iuir..,l  t..  buoy  this  particl..  must  .lisph,,...  at 
l.'a.st  .,2  msr.  wat.-r  .,r  in  otln'r  w.,r.ls  its  volum."  mii.st  1...  52  mm 


QQ' 


siii^'  th..s..  fi>,nir..s  tli.'  ..(piat 


IL'.'JO  "'■  fi.ssumiiif,'  the  ..|iarg..s  to  be 


.liam..ter  w.nil.l  b..  about  .",.2 
for  force  b..(.om,.s  52  (dynes 
bnlan..<.(l 

Q=  =  6715.92 

Q    =^  25.0  e.  fr.  s.  ..le.tro  stati.-  units. 


Its 


ir  IS  not  lik,.|y  tliat  a  jiartu-le  of  ore  or  a  bubble  of  the  nature  .nveii 
••an  have  a  charge  of  this  magnitu.ie.  for  (he  rea.son  that  a  ,).,tential 
of  Hns  intensity  w.ml.I  dis.-harsre  thr.m^'h  a  very  siron-  .li..l..,.tric. 
E.xi.rrimeiu,-.  iuiu-  been  carried  out  tliat  give  ratios  for  el..,.tr.,-static 
nnifs.  potentials,  ami  .lisfan,...  throufxh  which  .liseharge  will  take  ida...- 


Tin:  i;i.i:cru()  siMics  hk  ii.oi- vtihv 


341 


K!(  rtro-statlr  units. 
IC.l 

S4.7 


Volts.it  (lis 
chaiKf  iiotciitiiil. 
4s:!0 
]»iS90 
2r)-t04 


Distance 
lictwcin  l<nol)S. 
0.1  cm. 
0.5     " 
1.0     " 


.Xccoicim^r  t(,  thfsc  tirnivs  tlif  .■liarjre  tiiTfSNiiry  to  exert  a  force  of  fjO 
il.viics  ill  liftiiit,'  ,1  |>aili(le  (>['  iralciia  would  he  so  iiiteii.sc  thai  it  wouhl 
(lischari^e  throiif:h  a  dielectric  a.s  .strong;  as  air  at  tiie  distance  hy 
which  the  centres  of  diarires  arc  sef.arati'd.     Xdt  .sjitisficd.  Imwevi^r, 

with    tiiis    ai)|iareiit    theoretical    dLsjirovai    of    the    electric    tl ry    [ 

undertook  a  series  of  e.xperiiiients'  tliat  .should  serve  to  check  the 
varicius  points  in  the  ahove  theoretical  discussion. 

Xo.  1.  (ialeiia  ore  was  ^'roulld  in  an  a^ate  mortar  and  |)oured  from 
ill!  airatc  spoon  (to  prevent  discharsie  of  jiositive  elctricity.  if  present, 
from  ore  hetween  two  [ilates  of  an  electro-static  mai-hinc.  The  ma- 
terial was  derieeted  as  shown.  I'lates  were  eleetrilicd  almost  to  dis- 
charge point.  This  shows  that  pilena  liround  under  iiisiilatiiitr  eon- 
ditions  carr'is  a  <-liar";e  and  that  a  parti(de  of  this  nature.  :ius|)cii(led 
in  a  iioii-cnii(hi,ti,r  in  an  elcetro-statie  field,  is  attracted. 

Xo.  2.  Ore  wa.s  frronnd  in  eonduetiii<r  earthed  mortar  and  poui'ed 
from  earthed  spoon.  Deflection  of  only  a  very  few  particles  was 
.shown.  Perhaps  the  deflected  partielos  were  insulated  with  oil  or  did 
not  come  in  contact  with  earthed  surface. 

No.  :!.  Ore  treated  as  in  \o.  1  and  ixmred  hetween  glass  .si(h>s  of 
ii.  eell.  (Mass  was  1  mm.  thick  and  separated  hy  2  em.  Potential  he- 
tween plates  of  maeliino  was  S.")00  volts  Deflection  as  .shown,  The 
interposition  of  glass  had  very  little  etVeet. 

Xo.  4.  As  in  No.  :{,  hut  the  cell  was  full  of  water.  Used  conduc- 
tivity, tap,  and  aeid  water.  Xo  deflection.  This  indicates  that  par- 
ticles charged,  or  otherwise,  suspended  in  a  eondueting  solution  (i.  c. 
eiudosed  within  mir  hypothetieal  eonductiiiL'  -pliere)  is  not  affected  hy 
eleetro-statie  forces  without. 

No.  .").  Cell  contained  ore  and  nitric  acid  .solution  to  generate  ga.s. 
Xeifher  liul.hle  ri.sing  or  ore  particles  dropping  sliowed  deflection. 
Potential.  10.000  volts.    The  conditions  here  duplicate  those  of  No.  4. 

No.  »;.  Ruhhles  hlown  through  canvas  into  water  or  acid  solu- 
tion were  not  deflected.     A  charge  of  huhbles  flowing  in  one  direction 


•Tile  wiiicr  is  ,m-eaiiy  iiideiitea  to  the  (leiiartnu  nts  of  MetallurRica!  En- 
gineering and  of  Pliyslcs  in  the  Case  School  of  Applied  Science  for  laboratory 
facilities  and  apparatus  i)laced  at  his  disposal  in  carrying  out  these  ex- 
periments. 


:}42 


IMl:    I  l.ip|\TI(lN-    I'ROCTSS 


WonM  pn,,Iu,.,.  an  ..l.v.n,- nnw.MU.  and  ,.v,.Mr  HH.y  ...,.,.  ,.l,a,.,.,i  ,),,.v 


'•HiKluctiiii:  iiial.-rial. 


—Ti 


lJ 


~0 


F    .•■  'i 


rial 


FlC  i 


^■^-y 


Alt   »V'r^ 
-   CHAffrrBD 
P  -f /T  - >c  L.  E S 


Fkj.  79. 


,    ,  ■■  ,^';^"j^°"'-"'  ""«  f<-^ll  containing  gasoline.     Th-re  seemed 

h     ,H  ^''f  \^.i'^«'^^-*-"-    lO.noO  volts  between  plates.    Con,litions  here 

should  not  ditfer  greatly  fron.  those  of  No.  .1     Solut ,^a^  not  havl 

been  sufhciently  non-condtietin". 


iiii.  i:i.KciH()-.s-i'ATics  DC  ri.oixiroN  :j4:| 

No.  .S.  SolutKiii  nl.icd  in  cl-Ttrnlytic  ,rll.  .-uT.-iiiu'.d  us  shou,,,  ^rav 
iM.  .l.^Hcotiuu  „f  „rc  or  InhhU-  .Niti,  coiKiiictiii^'  ,„•  iiou-.'oii,|ii,ii„^  so- 
liilion,  Holli  icns  ati.l  chaa'cd  c.illoi.ls  in-v  swsccptil,!,.  t„  tliis  irrat- 
m'l.t,  1111(1  no  (loiilit  they  would  mov.-  fasier  than  tho  lari;.T  1m  jy  an,l 
so  lessen  the  potential  on  (he  larger  niasx.s. 

No.  !t.  Tile  \v;it,  ,•  itsrlf  was  eleelnily/.eil  to  fiiniisli  (.ms.  A  tun- 
way  switrii  save  either  iiy.lroK,  n  or  oxygen  at  the  l.oliom  poh,  uhidi 
was  eovere.l  uith  a  layer  of  ore.  Both  gases  .-arriea  apparently  e-pial 
iiMi.Mints  of  ore  and  with  e.pial  readiness.  Hiihhles  in  either  ea.se,  upon 
linking  the  ui)per  plate,  did  not  diseharge  their  luirden  of  ore,  no 
matter  what  the  sign  of  elect  mile. 

No.  10.  S<.t  up  as  ill  No.  ;t,  exeerit  that  s,  s  was  furnished  l,y  action 
of  nitrie,  acid  on  ore.  ( •haniriug  of  siirn  produced  no  discernihle  etreet 
upon  buhblo  or  ore  or  upon  huhhles  with  load  when  eoniin^'  in  contact 
with  upper  electrode  plate. 

r  wish  to  point  out  the  fact  that  tliis  .iis<'iis.sion  and  these  results 
are  to  he  eonsidered  only  in  connection  with  the  h.,n.:  between  a  bubble 
and  ore  particles.  The  eondition?  ehosen  have  Ixui  ideal,  in  ord.-r 
to  isolate  this  particular  plia.se  of  the  problem.  Particles  of  ai>preci- 
ahle  nia.ss  f+200-mesh)  have  been  u.s<>d.  but  this  permits  of  an 
eleetro-statie  eonsideration  without  interferenee  I'rom  exat^'erated 
.surfaee  conditions  due  to  smaller  bodies.  It  is  po.ssible  that  an  "ionized 
solution  does  not  behave  like  a  .solid  metallie  coiiduetor  toward  an 
eleetro-statie  eliarge.  but  I  know  of  no  evidenee  to  the  contrary.  Very 
little  is  known  regarding  eontaets  betw.-en  solid-liquid-gas  phases,  but 
it  is  (buibtful  whether  eharges  sueh  as  ,.  ■company  phases  of  a  colloidal 
solution  are  of  much  influence  in  the  ca.s,^  of  bodies  of  the  ,size  herein 
eonsidered.  It  may  be  found  that  the  oil-water  emulsion  or  the  oil- 
films  intrr.duee  the  colloidal  element,  and  no  doubt  many  of  the  slimes 
contain  colloids,  in  which  the  electric  charges  are  of  gr..at  importance. 
It  is  known  that  masses  of  sulphides,  sueh  as  galena,  are  positive,  but 
Assiime  edge  of  ^^^^^^^ 

'^"^•^  *"  *"'  NiiMber  of  cubes.  SurfacP. 

1  cm     1 

i  »)  cm. 

"•'  "        10'  fio  •• 

"■01       •'      10-  coo  ■• 

0-"01       "        10'  6,000" 

1.  )nct     "       (one  micron   (u)) m"  (1  sn  m 

n.0005     "        (size  of  nartiolrs  In  W.inlin  susppp^ifini 

0.00001  =  micron   iq.'  rq  .,  .. 

0.01  micron  (limit  of  ultra-mirroscop.v) .   10"  600  "  " 

0.001         ■'       =  one  millimicrn    fniii)...   10"  e.OOO  "  " 

0,1     mu.  =  hydrogen  molecule lo"  €0  000  "  " 


344 


rilK    I'LUTATIOX    I'UOCF.t.S 


fli.'s,'  same  suVlu'l^.s  ui  .•..ll„i,ial  fonu  aro  ii.'gative.  Metals  in  mass 
and  as  atoms  aiv  ix.sitiv  Imt  these  also  as  eollaids  are  negative. 
This  eomplie.ites  cr.nsid.rahiy  the  eleetrieal  theory  in  the  ca^e  of  pulp 
containinsr  l.oth  sami  and  slime.  It  may  he  interesting  to  eall  attention 
to  the  enormous  increase  of  surface  produced  hy  .suhdivisinn,  in  which 
<-asc  [.jicnomcna  that  are  purely  superficJMl  are  greatly  ..nhanced. 

AVhen  it  is  considered  that  these  small  particles  contain  the  energy 
iieeessary  to  subdivide  them,  whether  electrical  or  otherwise,  it  is 
appare-it  that  i)lien(,mena  .  ncouiitered  throughout  a  range  in  size  of 

particle  iiody  will  not  h.'ar  a  dit t  ratio  to  its  mass  or  constituent 

material.  A  consideration  of  this  phase  of  the  suliject  is,  however, 
without  the  s.-ope  of  this  i)a|.er.  wiiicOi  is  only  given  to  point  out  a  few 
of  what  would  ai)i.ear  to  he  iiii,sni)i)lications  of  H,,.  laws  of  electro- 
statii'M. 


ON  THE   SCIENCE   OF   A   FROTH 

By  Wii.i.  IF.  ('()(;iiu.i. 

(Fioni  tlir  Miniii;/  and  Srinitifir  Press  of  I'>!)riiary  2(;,  lOltl) 
'I'll''  paragraph  .,n  tli..  character  of  froth  in  Mr.  Callow's  article 
in  the  Mniim,  ,iml  Sri.ntijir  I'n  s,  of  December  4.  l!tl.-).  page  S.")!',  I^d 
me  tu  ,-erer  to  .some  not,  s  that  have  been  pigeon-hole<l  for  some  months 
1  thuik  that  a  little  mathematics  can  he  applied  to  good  advantage. 

Helo.v  taking  up  t'  e  n.atliemati..s.  Imwever.  1  wish  to  mentirn 
soni.'  pnnciples  that  I  mink  have  not  been  suilicientlv  cuphasl/,.,]  in 
the  aiticles  on  Hotation:  that  is,  a  distin,lion  betweea  the  properties 
ot  afpieiais  and  non-a(|iieous  tilms. 

The  little  book  on  'Surface  Tension  and  fturfaee  Eiiertry'  by 
Willows  &  TIat.sehek  shows  how  the  elastic  tilm  aiud,.gv  in  th.^'studv 
ot  troth  will  get  one  into  no  end  of  trouble  if  not  handlcl  with  care 
It  IS  the  ••hanicteristie  of  anah.gies  to  break  d,.wn  wlwn  pres,se<l  too 
tar.  though  they  ar.'  useful  up  to  a  certain  point.  This  one  is  no  ex- 
eei)1ion.  In  the  ca.se  ..f  india-rubber  it  is  obvh.us  that  a  'nven  wei.'ht 
can  only  siretcl,  this  to  a  definite  extent.  To  |-nrther  enlarsre  Hie 
nibiur  tihn.  an  a.lditional  weight  wouhi  be  re.,uiiv,l:  while  wMh  a 
l"l>'id  tilm  this  is  not  true.  R,.ferenee  to  a  recent  arli.de'  sh.nvs  that 
the  moasure  of  surfac<.      osion  is  not  when  the  lilni  br.'aks  but  at  the 

'T.  A.  lii<Kai.l.  .1/.  .1  .s.  /'.,  Se;it.  11,  Ittl,'..     Sec  page  i27. 


ox  THE  SCIKNCi;  UP  A  FKUTII 


34'' 


a  great  distance  witlioiit  breaking  tlie  lilni.  tlie  total  cnorgy  of  the 
surface  is  incre.m'd,  of  course,  hut  tlie  energy  per  unit-area  and 
surface  tension  are  uiiatVeeted.  Whether  or  not  the  (ilm  i.reaks, 
depends  not  upui:  the  surface  tension,  l)ut  whether  or  not  there  is 
enough  liquid  to  supi)ly  the  added  area.  The  ditVerenee  hetween  a 
non-aqueous  substance  and  a  liipiid  lilm  is,  that  in  stretrhing  the 
foniier  thi'  molecules  are  distorted  or  separated  while  in  stretching  a 
liquid  film  molecules  come  from  within  the  liquid  to  occupy  the  new 
area.  According  to  Devaux=  the  surface  tension  phenomenon  dis- 
appears as  soon  as  there  is  no  more  liquid  to  come  from  within.  The 
same  laws  apply  to  surfaces  that  arc  allowed  to  contract.  Tlie  rublicr 
lias  a  constantly  decreasing  force  of  contraction  as  it  approaches  its 
original  dimensions,  while  a  liquid  film  always  tends  to  contract  with 
the  same  force  independently  of  its  size.  Now,  it  is  a  common  practice 
in  demonstrating  physical  principles  to  omit  certain  qualifying  con- 
ditions until  the  u\H  features  are  outlined.  This  ttiefhod  must  be 
pursued  here.  The  .ijalifying  statement  is,  that,  in  tlie  ca.se  of  a 
contaminated  liquid  the  film  may  not  "contract  with  a  force  independ- 
ently of  its  size;"  that  is,  after  learning  to  look  upon  surface  tension 
as  a  constant  force  we  must  now  view  it  as  a  variable  force.  Take. 
for  example,  the  explanation  of  the  effect  of  oil  on  waves.^  Wiicn 
a  small  wave  is  formed  on  the  surface  of  water  the  surface  is  .stretched  : 
for  obviously  the  wavy  surface  has  greater  area  than  the  plane  sur- 
face. Owing  to  the  stretching  of  the  surface  the  oil  film  is  made 
thinner  so  that  the  contamination  duo  to  oil  is  reduced,  and  hence  the 
surface  tension  is  increased ;  this  increase  in  surface  tension  tending 
to  oppose  the  production  of  the  wave. 

Again.  Edser*  discusses  variable  surface  tension  under  the  head- 
ir.g  'Stability  of  a  Liquid  Kihii.'  Tie  shows  that  when  a  film  is  o!i  a 
vertical  rectangle"'  equilibrium  is  impossible  uidess  the  surface  tension 
is  greater  at  the  top  than  at  the  bottom  of  the  film.  This  is  obviously 
due  to  the  weight  .  ihe  film  it.self.  For  pure  water,  the  surface 
tension  is  nearly  or  .,nt,  and  therefore,  a  water  film  more  than  two  or 
three  millime'res  in  height  cannot  be  formed.  A  slight  trace  of  grease 
will  give  the  water  a  variable  surface  tension  :  if  the  surface  tetision  at 
any  point  on  the  film  is  insufficient  to  produce  equilibriuiu.  the  film 


-'Oil  Films  on  Water  and  on  Mor.ury."    .1/   ,f  .*J.  p.,  .inly  :n,  1915. 
^.I.   W.  Watson.  'General  Physics.'  paKe  11.'?. 
•"Edwin  Elisor,    ueneral  I'tiyslcs  for  Students,'  paKe  34S. 
•The  fut  of  the  reotanRle  was  shown  in  the  artiole  pr.'vloiislv  referred  to 
In  the  M.  <f  S.  P..  Sept.  11,  ISI.^). 


346 


THE    1I,0TATI0N    I'KOCESS 


stn-tdu.s  at  tliis  point,  and  tlie  conc-entration  of  greaso  is  diniiuislu.,1 
so  tliat  the  surface  t.-nsion  increases  automatically  and  cquiiil.riuni  is 
iiiamtaiued. 

He  <unrlndes  l,y  savin-  tlial  tlie  -,vat  stability  of  a  soap  lilm  is 
'liie  to  the  wide  variation  in  snrfa.'e  tension  l.etw.vn  fr.'shlv  for.ne.l 
aud  ].,n-  ..xp,,srd  parts  ,,r  il„.  snrf.ir,.  and  that  anv  streteliin-  of  the 
'"I'll,  due  to  insuftirient  streii-tii,  iu.inediatrly  in.-re.-ises  the  surfa,-e 
tension.  Now  It  seems  to  me  that  it  is  time  for  us  to  set  awav  from  the 
Idea  that  low  surfa-e  tension  prr  sc,  is  necessao"  for  tiie  formation 
ot  a  troth,  for  Edser  has  made  it  elear  tiiat  the  eontamination  of  the 
hhu  wi,h  somrthin-  tluit  will  Rive  a  variahl,.  surface  tension  is  the 
esseatial.  To  be  sure  this  amounts  to  redu.in-  surface  t.-nsion  because 
contamination  of  water,  with  some  c.xcepti,uis.  lias  this  elfect  The 
attorney  who  discoursed  at  -reat  length  upon  surface  t.'usion  and 
said  that  tlie  longevity  of  a  bubble  was  inerea.sed  bv  decreasing  the 
contractile  drawing  force  of  surface  tension,  was  merely  riding  too 
tar  111',  willing  iiorse  that  many  of  us  have  ridden  so  freely. 

!t  is  quite  easy  to  accept  the  statement  that  soap  contaminates 
water  enough  to  afford  a  variable  .surface  tension,  but  it  is  not  .piite 
so  clear  how  a  very  small  fraction  of  1%  of  oil  will  give  the  same 
results,  until  we  have  considered  adsorption. 

Adsorption  has  been  described  several  times  m  the  technical 
journals  but  I  believe  I  am  .iustifie.l  in  taking  it  up  again  and  quotiiu; 
trom  -Surfac..  Tension  and  Surface  Knergy,'  because  here  we  find  the 
generalized  statement  describing  adsorption  in  a  liquid  and  its  effect 
on  surface  tension.  It  says:  "If  the  dis.solvcd  substance  diminishes 
the  surface  tension  of  the  .solution,  an  excess  of  concentration  in  the 
surface  layer  diminishes  surface  energy.  If  on  the  other  hand,  the 
solute  increases  the  surface  tension  tli(>  surface  energy  will  be  reduced 
if  th.'  concentration  in  the  .surface  layer  is  Iow.t  than  that  of  the  bulk 
of  the  solution.  This  ditference  in  concentration  between  the  surface 
Ia.v(.r  and  the  bulk  of  the  sfiiution  is  called  adsorption  and  is  a  physical 
fact.  The  fjictors  tending  to  produce  adsorption  are  opposed  to  th" 
factors  tending  to  establish  uniform  concentration.  The  final  dis- 
tributi(wi  of  a  solute  is  the  resultant  of  adsorption  and  two  other 
cfTects,  namel.v.  osmotic  pressure  and  electric  charsje.  Important 
qualitative  conclusions  are  drawn  from  theoretical  considerations 
already  developed.  A  small  quantity  of  dissolved  substance  may  re- 
<luee  the  surface  tension  very  considerably,  but  it  can  onlv  increa.se  it 
-::;;:.:;;. .  ;  :;;:o,  ;;."aram  cnionUe  lucreaw's  surface  tension  ot  wat(>r 
♦o  a  small  cNtent;  the  "oneentration  in  the  surface  layer  is  accordimzly 


ox  THE  SCIENCE  OK  A  KROTII 

sNiallor  than  ii.  the  bulk,  and  the  etlVct  of  the  solute  is  thus  partly 
••ounteracted.  On  the  other  hand,  many  organic  salts  reduce  surface 
tension^  and  therefore  accumulate  in  tiie  surface  layer;  so  that  in 
.xtreine  eases,  the  whole  of  the  solute  may  be  eollceted  there  and 
pid.lu.v  a  considerable  elTect,  although  the  absolute  quantity  may  ho 
exceedingly  slight." 

Adsorption  is  of  such  unmistakable  importance  that  we  will 
refer  to  'The  Chemisti-y  of  Colloids'  by  AV.  W.  Taylor  for  a  different 
perspective  of  the  same  thing.  Here  I  quote  freely,  for  I  am  not 
intending  to  advance  my  own  theories  but  to  l)ring  out  wliat  seem  to  me 
to  be  the  pertinent  physical  facts.  And  here  I  wish  to  state  that  I 
fear  that  the  premi.se  for  my  recent  calculation"  of  the  carrying 
capacity  of  the  surface  of  a  liquid  is  not  correct.  It  was  an  attempt 
to  elaborate  on  a  weak  statement  in  a  text-book  and  hence  the  calcu- 
lations themselves  cannot  be  credited. 

Adsorption,  in  its  most  general  sense,  implies  the  unequal  dis- 
tribution of  substances  at  the  boundary  between  two  h»tcrogeneous 
phases:  solid-gas,  solid-liquid,  and  litjuid-ga.s.  We  are  concerned 
just  now  with  only  the  last. 

The  surface  layer  of  a  liquid  is  under  great  comi)ression  due  to  the 
■great  difference  of  the  molecular  forces  on  the  two  sides  of  the  inter- 
face and  consequently  the  concentration  in  the  surface  of  a  solution 
must  be  different  from  that  in  the  bulk  of  the  liquid.  For  just  as 
unequal  temperatures  in  a  dilute  solution  cause  an  unequal  distril)u- 
tion  of  the  solute,  so  from  the  same  law  unequal  pressures  nuist  also 
produce  an  unequal  distribution.  This  pressure  (due  to  surfac  >•  ten- 
sion) always,  in  time,  adjusts  itself  to  the  miinmum.  for  a  component 
which  lowers  surface  ter-  n  is  always  increased  in  the  surface  layer 
whether  the  component  be  present  as  solvent  or  solute. 

We  now  hav(>  a  new  princii)!e  to  apply  to  a  bubl)h'.  to  wit:  on 
account  of  adsorption  a  fresh  surface  always  has  a  greater  surface 
tension  than  an  old  one;  thus  if  -t  is  stretched  locally  by  conditions 
tending  to  break  it.  it  is  automatically  reinforced  at  that  point. 

Tt  is  now  obvious  that  without  adsorption  it  would  be  impossible 
to  realize  a  variable  surface  tension,  for  if  the  solution  were  contam- 
inated uniformly  throughout,  a  fresh  surface  exposed  by  the  stretch- 
ing of  the  film  W(mld  have  the  same  energy  ps  the  old  surface  and  the 
ultimate  result  would  be  idcnti.'al  with  tlie  case  cited  where  pure  water 
w.ns  used- 

In  this  argument  I  have  assumed  that  the  contaminating  sub.stMuce 
•Page  IBS. 


348 


■I'm;    KI.()T\T|il\    I'KdC-KSS 


.s  s.,1,,1,1,.  i„  water.  1  n-alize  luUv  tl.a.  many  .,f  ,h,  H,„aii„„  „ils  are 
"'"""  '"'  '"^"l"l'l"  in  ^^iit.'r.  liut  I  luauitain  ,i,at  snl„l,ili,v  is  onlv 
'■•■'^'"■'■-  •'>',!  lurthrr,  we  knew  nothin-  „1„„„  ,|„,  .....itii.li.itv  ,,V 
;'l'"'""--'l  >va,-t:nn.s  po.ssiblr  in  a  pulp  wlm-l,  niifiht  release  conta.ninat- 
Uig  substances  that  w„ul,l  ,,nHluee  the  adsorption  pheno.nenoi.  If 
frraphite,  lor  mstanee.  acts  as  a  iVotliini;  a-ent,  it  niiirj.t  have  to  be 
"■<-te,l  as  a  sperial  ease  an.l  eonl,l  not  l,e  taken  as  proof  that  tlie 
above  arguments  are  invali,!.  If  the  flotath.n  .m1  is  eNtrernHv  insoluble 
'M.  an,]  l.jrl,,,.,.  than,  water  there  would  be  an  o,l  tilni  at  the  liquid- 
""•  I'lterlaee  and  ovrr  the  li,|nid  til.n  eontainin-  adsorhe.l  oil  Ft 
inisiht  be  well  at  this  point  to  ,lrop  the  subjeet  of  variable  surfaee 
tension  and  undertake  to  p.f  a  better  i.lea  of  the  absolute  value  of 
these  torees.    One  physieist  has  spoken  of  tlieni  as  bein<r  euorinous. 

As  far  a.s  surfaee  tension  is  eone^rned  it  is  theoretieallv  j^ossibl,. 
to  blow  a  soap  bubble  as  bifr  as  a  house. 

Take  the  forimila  : 

(1)      P^^"^ 
r 

AVh.'i-  T=r_.p„]l  ,],„.  to  surface  tensi,,n  in  frniins  of  a  tilin  of  one 

surface  and  1  em.  lontr. 

P-=  exeess  pressure  inside  per  unit-area,  and  r  .-=  the  radius  of  the 
sjiher". 

This  formula  takes  into  aeeonnt  the  pull  on  Imtli  1h.'  internal 
an, I  ,'xternal  .surfa,-es.  It  n,-,'ds  no  dem,)nstrati,.n,  as  it  is  ,l,.riv..,l  in 
the  sam,.  manner  as  the  ol,l  familiar  formula  used  in  eal,MiIating  the 
thiekiu'ss  of  boiliT-shells,  et,'. 

In  ,ase  ,if  a  li,iui,l  ,|r,)p  or  a  bubbi,.  .subm.Tged  in  wat,.r  the 
f,irmula  is: 

(-'1  1'^     -■ 

!• 

N',iw  l,t  us  use  tlu'se  formulae  to  make  a  little  studv  ,.f  the  math,'- 
...atM^s  of  .i  bubbl,.  to  s<M.  h,.w  i.ni,.li  a  variation  o.  surfa,'e  tension  an,l 
external  pre.ssure  amount  to  when  num..ri,'ally  .'Npn-ss,.,!  ami  .s.,.  if 
Jlr   Callow's  artjiiment  is  poo,!. 

II,  slal.>s:  -Tl,..  bul,-,)l,.s  •  *  b,.i„s;  prpn,.rat,.l  un,i,.  a  hv,lraiilie 
pressure  varying  from  M  to  4('  im^hes,  on  risin^r  abov,.  th,.  wat..r  *  • 
burst  by  r.'ason  of  the  lower  snrronmlin-  atmosph,'ri,'  piv.ssure  " 
Plus  pi,.|uivs  th,.  ,.m,.r<rinR  Imbbl,.  as  ,.xpan,ling  lik,>  a  bla.l,l,.r  when 
siid,lenly  inHat,..l  by  inerea.s.-d  internal,  or  d,'erea.s,>,l  ..xt,.rnal,  ,,res- 
sinv.  and  is  a  mi.s.-on,-eptioii.  T.,  mak-  the  steps  more  simi)!,.  w  will 
Mis;  .•,i,|,i.^   iiii.  biihbie  in  air  and  then  when  .submerfjed. 

.\s.sum,.  1  e,..  of  free  ;.••  triken  in  form  of  a  sphere 


ox  THE  SCIENCE  OF  A  KKOTII 


;J4!) 


r==  0.620  fin. 

Now  suppose  tliis  air  lo  hr  t'liclosfd  in  n  liquid  film  in  air  wlit^rc  tiie 
liquid-air  surface  tension  is  70.  Tiie  new  radius  can  he  calculated 
liy  the  ap|)licatioii  of  H(iyh''s  law.  which  is.  that  tli.'  pressure  varies 
inversely  a.s  the  volume,  where  ahsolut.'  pressure  is  of  course  under- 
stood. The  free  air  is.  in  round  nnmhers.  under  a  pres.sure  of  1000 
pm.  per  sq.  em.  ami  a  surface  tension  of  70  dynes  per  cm.  exerts  a  pull 
equivalent  to  weiirht  of  a|)proximately  0.07  pm.  per  em.  of  length. 

The  proportion  used  to  ealeulate  the  new  radius  is: 

1000    :    (1000 +  "_:'■"')    ::  4.2r^   :  1 

(4)  42(Mir-'  +  1.176r=r=100U 

r  =  0.61!» 

,,_  4T       0.2S 

^  —    r         0.i;i9  —  0.4O.5  gill,  per  sq.  cm. 

The  second  term  of  equation  (4)  is  the  only  one  that  contains  a 
function  of  surface  tension,  and  since  it  is  of  such  small  numerical 
value,  it  is  plain  that  any  variation  df  surface  tension  has  very  little 
to  do  with  the  radius  of  an  individual  huhhie  in  air.  Even  when  the 
surface  tension  varies  between  zero  and  a  maximum,  as  in  (3)  and 
(4),  the  change  of  radius  is,  in  fact,  too  slight  to  he  calculated  on  the 
slide-ruh — only  from  0.f)20  to  0.61  r»  vm.  It  is  interesting  to  note 
that  P  has  a  value  of  0.4r):i  gm.  per  sq.  i-m.  which  equals  0.006  Ih.  per 
sq.  in.  This  is  the  order  of  magnitude  of  the  forces  that  cause  a  spray 
above  the  froth. 

Xuppo.se  again  that  the  bubble  is  1  cm.  below  .surface.  We  then 
have : 

(5)  1000    :    (1001  -f  "J^  )-=4.2r'    :  1 
r=:  0.618 


Total  pres.sure  1  +  0.226^1.226  (gauge) 
Finally  take  a  depth  of  75  em. 
(61      1000    :    (1075  +  2Ji_)    ::  4.2r^  :  1 
r=.  0.561 

Totnl   nro-iRure  =^  75  -I-  0  250  ^^  7^,  9^.0.    Z .-ra-.^ .-?.-. 
Ihcse  result.sare  shown  in  the  appended  table: 


350  THE    FLOTATION-    PHOCESS 

OM;  (  L  liU    LhMI.MKTHE  HIKK  AIH 

No.  Description.  r  p  ^'''"''''  ^^''^"lute 

3  Free    nir  n    ,„  inessiac.         pirssure. 

"""""•^«"'  -^ -" <^-'>l  0.250  73.25I;  ;So50 

C'olu.n,.  ,•  shows  that  a  hubble  emerges  with  at.  t.Uin.tely  Muall 
e  ange  oi  .aduus.    1,.  f.,,  the  ehauge  t.  „n  the  shle  of  deerea.>  be     us 
oi  the  surlaee  hhu  bei.g  doubled.     Now,  sn-ee  there  is  pruet.ea   y  r" 

me  tl  at     lov   surr  .uiuhng  at.uospherie  pre.ssure"  has  nothing  to  do 
ah  bursting  m.  CalhnVs  bubbles.     Of  eoui.e  it  ,s  well  known  that 

I'ueas  ,1    t  ts  l>urst  in  air  it  is  evanesc-ent,  but  it  is  necessary  for  the 
"""lilMrg.st  to  study  tiie  te.vture  of  these  bags 

Sinee  a  bubble  does  not  expand,  how  are  we  troing  to  aeeount  for 
4-u.eh  bubbk.s"?  By  coaleseenee  (unless  electrifieation  p  -s  1 
part).  Sometimes  they  cohere  but  do  not  coalesce.  AVh  n  .  e  • 
coalesce  the  large  one  robs  the  small  one  because  pre.s.sure  varie  - 
ver.ely  as  the  radius  (.see  Equation  1).  The  little  one  'pumps  "ts^^s 
n.to  the  large  one.     We  shall  have  to  learn  how  to  control  codeseeiL. 

along  ^^  h.  ^a,,able  .surta-e  tension  and  coalescence.  It  is  not  surface 
tension  that  breaks  bubbles,  but  it  is  blows  upon  a  surface  that  a'k 
v.sc.osity  or  toughiu.s  and  variable  surface  tension,  that  eau.se  rupture 
They  nipture  easily  on  account  of  lack  of  friction  of  the  moleciiles' 
\V.  h  low  friction  a  blow  is  likely  to  cause  the  molecules  ,0  be  sepa: 
ra  cd  a  distance  at  which  surface  tension  phenomena  disappear  before 
•  '-  ...olecules  have  time  to  come  from  below  and  reinforce  the  area 
with  their  greater  surface  tension. 

cosi'tv'.'nlT''''  'f.'"''''^T"  '^'  ^^PO'-t^^^^  Of  ^eat  superficial  vis- 
;^o,sit>   ad  small  ,„,ernal  viscosity  for  the  persistenee  of  a  fn.th      It 

;s  said  that  alcohol  which  has  a  superficial  vi.scositv  le..s  than'  the 
i-lemal  viscosity,  when  mixed  with  supcrfieially  viscous  liciuids  will 
neu  ra  e  the  relative  surface  viscosity  and  make  frothing  ilpo.sible 
Hen  ..  the  practice  of  a.lding  a  few  drops  of  alcohol  to  check  frotbin.^ 
u,  Pharmaceut.cnl  work.  We  know  that  tannin  sometimes  interfere; 
^^.  h  flota  ion  work  and  also  that  it  may  form  a  colloidal  solution  with 
water.     Afnv  \va  ,.^f  „.!,]  ii._i  _i,-i    ,     _,   .        . 

-  .  '"'  '•■"'-  "■"^'"!'i  a.iia  taiiiiiu  an-  deterrents  he- 

cause  adsorption  is  cliecked  on  account  of  ■:ntemal  viscosity  produced 
".^  them  .     For.  without  adsorption,  one  of  the  leading  factors  tending 


SMKLTING   KLOTATIOX    CONCENTKATE 


351 


to  prodiuf  u  stable  froth  is  miUitk'd,  tlial  is,  varialile  surfacf  tension. 
Jly  best  thanks  are  due  to  Dr.  W.  B.  Anderson,  profe.ssor  of  physics 
in  the  College,  for  his  helpful  sugprcstions  and  criiiral  readiiisr  of  these 
notes. 


SMELTING  FLOTATION  CONCENTRATE 

(From  tlie  Miiiimj  ami  Svi<:ntifu  I'irss  of  l-Vljniary  IJ,  I'Jii;) 

In  the  November  issue  of  Tcnicntc  Topics,  the  monthly  publication 
of  the  Hraden  Copper  Co.,  Chile,  a  meniher  of  the  staff  briefly 
outlines  the  developm.  iit  of  the  smelter  from  190!)  to  the  present 
time,  iletallurgical  difficulties  have  l)een  'iiaiiy,  l)ut  were  overcome, 
in  spite  of  being  GOOO  miles  from  the  base  of  supplies.  The  plant 
now  treats  350  tons  of  concentrate  daily,  yielding  60  tons  of  copper, 
during  which  operation  60  tons  of  coke  and  10  tons  of  fuel-oil 
are  burned,  employing  350  men  and  1500  hp.  This  (piantity  of 
concentrate  is  recovered  from  4000  tons  of  ore  crushed  per  day. 
The  concentrate  consists  of  19^,'  copper,  17^0  silica,  23%  iron,  2% 
lime,  8%  alumina,  and  28%  sulphur.  It  is  sandy  and  .slimy,  and 
contiiins  20%  water.  Of  the  350  tons  of  concentrate,  about  215  tons 
is  dumped  from  V-shaped  steel  cars  into  bins,  which  supply  the 
nodulizing  kilns.  This  concentrate  is  then  fed  to  conveyor-belts, 
thence  into  kibis,  heated  by  oil-buniers  to  a  temperature  of  1750°P. 
In  the  kilns,  the  sandy  concentrate  is  (piickly  heated  by  the  burning 
of  the  oil.  and  also  by  the  combustion  of  a  part  of  the  sulphur  content, 
to  a  sticky  consi.itcnce,  in  which  state  the  rolling  motion  tends  to  ))all  it 
into  nodules  of  \ar>ing  size.  The  kilns  are  sloped  an  inch  per  foot 
toward  the  discharge-end,  out  of  which  the  red-hot  nodules  pour 
onto  an  endless  chain  of  cast-iron  pans,  which  convey  the  product 
to  hoppers  ready  to  charge  into  the  blast-furnaces.  The  nodules  have 
about  the  s.ime  chemical  content  as  the  original  concentrate,  except 
that  the  proportion  of  sulphur  has  (wen  reduced  from  28  to  18%, 
and,  of  coui'se.  the  moisture  has  l)een  evaporated. 

A  by-product  of  the  nodulizers  is  flue-dust,  that  is,  .a  small 
proportion  of  the  concentrate  blown  out  by  the  draft  in  the  kilns 
and  caught  in  dust-chambers,  removed,  and  hauled  +0  the  bins  for 
re-treatment. 

Another  50  tons  of  the  original  concentrate  is  .sent  to  bins  th.at 
discharge  to  the  sinter-plant,  of  four  units.  Each  unit  is  a  concrete 
box.  4  ft.  wide  by  50  ft,  long.  In  place  of  a  top  there  is  a  oast-iron 
grate  similar  to  that  of  a  stationary  boiler,   but  with   smaller  air- 


;j52 


TIIK    KI.OTATKIN    I'KOCKSS 


iH.l.H.  Au  ...xl,a,i.sf-ta„  is  ,.„„no,.t,.,l  fo  tho  l,ox.  .Toatinff  a  strong 
d'.WM-dratt  ot  air  tl,r,.n,.h  tlu-  ^v.u,  A  4-in.  lay.r  of  rau-  .■..ncentrate 
IS  spr-ad  .a  flie  ^M-af  will,  an  inch  lay.T  of  saw-,]„st  ijx,n.,..l  with 
kerosene  ..r  gasoline  torel.es.  after  the  fan  has  been  started  The 
s<iw-dnst  starts  the  eomhnstion  of  the  sulphur  in  the  <.oneentrate' 
I  Ins  then  eont.nues  to  roast  for  an  hour,  when  the  sulphur  is 
redueed  to  12%  an.l  the  loose  layers  are  ro.lueed  to  a  hanl  cake 
llu'  cak."  IS  broken  into  pieees  six  to  eight  inches  in  diameter  a-,d 
raki'd  into  cars  that  go  to  the  bliist-furnaees. 

The  nnuuning  85  tons  of  concentrate  received  <lailv  is  discharged 
into  bins,  thence  fed  by  conveyors  into  cars  direetlv  to  the  blast- 
turnaccs;  this  amount  being  smelted  raw. 

Tin.  two  blast-furnaces  are  25  and  30  ft.  long,  rcspectivelv  4  ft 
wide  and  9  ft.  deep,  with  hollow-steci  water-jackets.  The  fnrnaces 
are  fed  w,th  a  charge  consisting  of  varying  proportions  of  noduli/e.i 
sintere.l,  and  raw  concentrates,  together  with  converter-slag  (con' 
taining  60%  iron)  a^  a  flux,  and  coke  as  fuel.  The  proportion  of 
.•oke  to  concentrates  averages  about  15-?.  and  is  dependent  <li,-ectly 
on  the  amounts  of  raw  and  nodulized  concentrates.  This  mixture 
gradually  sinks  in  the  furnace,  becoming  hotter  and  continually 
melting,  until  m  the  bottom  it  is  liquid  at  a  temperature  of  2500°P 
and  runs  into  the  settler.  The  matte,  containing  45-;  copper  :{(y;,' 
iron,  and  25%  sulphur,  remains  in  the  settler  until  removed  throu-^h 
a  hole  near  the  bottom  and  poured  into  the  converters  through^ 
brick-lined  launder. 

The  converters  are  of  the  Pierce-Smith   basic-lined  tvpc      Ea.'h 
consists  of  a  horizontal   cylindrical  siieet-stcel  shell  25   ft    long  liy 
10  ft.  diameter,  inside  of  which  is  a  lining  18  in.  thick  ,  f  magnesite 
bnck.     This  material   is  not  attacked  by  the  chemical   reactions  in 
the  converter,  and  consequently  lasts  for  a  long  time,  unl.'ss  allowed 
to  over-heat.     The  cylindrical  converter-shel'  rests  on  heavv  rollers 
an,,   e.ui   be   revolved  around   its  axis  so   as  to  emptv  its' contents 
throH-h  a  hole  in  the  side  when  necessary-.     The  converter  is  pierced 
by  a  horizontal  row  of  blast-pipes  through  the  sheet-steel  and  linin<r 
for  the  entrance  of  compressed  air.    These  holes    re  in  a  line  parallel 
with   the  axis  of  the  cylinder  somewhat  below   the  c,.ntre.line    and 
point  down  toward  the  bottom  of  the  converter      A  large  hole  in  the 
top  receives  the  charge  of  matte,  and  serves  as  a  chimnev  for  the  escape 
of  gases. 

When  ready  to  receive  a  charge,  the  converter  is  revolved  until 
tho  mouth  is  under  the  end  of  the  matte-launder  leading  from  the 


itr-J 


mmimmm  ' 


SMELTING  FLOTATION   CONCENTRATE 


;J5:J 


settler  mentioned;  this  position  plaees  the  tuyeres  at  about  the  centre- 
line of  the  cylinder.  A  stream  of  !iiatte  is  run  by  gravity  into  the 
mouth,  until  the  eoi.  /erter  is  filled  almost  to  the  level  of  the  tuyeres. 
There  is  also  added  a  small  amount  of  quartz.  Compressed  air  at 
10  to  12  lb.  pressure  is  then  forced  through  the  tuyeres  and  the 
con.erter  is  revolved  until  the  tuyeres  are  submerged  about  12  in. 
under  liquid  matte. 

The  elimination  of  the  iron  and  sulphur  leaves  practically  pure 
copper  as  the  only  remaining  constituent  of  the  matte;  after  12  hours 
of  alternate  blowing-in  air  and  pouring  off  slag  a  bath  remains  of 
25  to  ;i()  tons  of  molten  copper.  This  goes  into  ladle-cars  and  is 
hauled  to  a  receiver,  which  is  simply  a  laige  bri<k-lined  kettle  capable 
of  lifting  and  pouring  its  contents  into  a  series  of  moving  cast-irop 
molds. 

The  copper  solidifies,  is  removed,  and  carried  to  a  platform  to 
be  loaded  on  cars  for  shipment.  This  final  product  is  known  as 
'blister'  copper,  on  account  of  large  blisters  or  bubbles  of  giis  formed 
on  the  surface  of  the  bars  while  cooling.  The  bars  run  99.5%  copper, 
and  average  220  pounds  in  weight. 


354 


Tin;  n,iiTATi()\   I'nocfss 


FLOTATION  ON   DUMP  ORE 

(From  the  Munn,j  ami  li,,entiflc  Press  of  Uer.-nih.  r  11.  mr.) 
Tlic  Kditiir: 

Sir-()„  11,0  ,.vo  ..r  Miy  ,i,.,.,nt„n.  (nnn  Australia  I  n.vivvd  a 
copy  ot  y,.„r  ,s.s„e  „f  Jt.ly  in,  i„  which  co„si.lernhl..  (.rottuttcnce 
was  ^.vot.  ,„  the  s.th.i..,,  „f  flotation.  a„d  it  has  o.-cLd  to  2 
that  the  lollowu.g  ...ay  i.o  of  interest  to  some  of  vour  readers 

harly  last  year   I   wa.s  eoni.nlHsione.i  to  re-o,-sra,.ize  the  work  of 

the    Lloyd   topper   (,o,„pa,.y   at   JJ.irraga,   New   So.ith    Wales    and 

upon  ,„y  arnval  there,  found  that  the  concentration  n.ill  had  been' 

oq...pped  recently  with  tube-.nills  and  a  flotation  unit.     I  need  not 

go  L.rther  .nto  the  .lescription  of  the  plant  tha,.  to  state  that  when  I 

assumed  command  the  output  of  the  mine  and  of  the  s.nelters  was 

hm.  ed  by    l.e  capacity  of  the  mill,  which  waa  not  working  as  well 

as    t  sho.i  d  have  been  doing.     Attentio..  was,  of  course,  first  given 

to  the  mill,  which  so  well  responded  to  the  efforts  made  that  before 

long  1    outstripped  the  supply  from  the  mine,  which  was  suffering 

sadly  the  consequences  of  lack  of  development.     In  the  meantime  I 

had  made  laboratory  tests  with  regard  to  the  flotation  of  the  tailing 

lying  on  the  dumps  and  had  also  sent  away  sa.nples  for  trial  at 

he  expenmental  works.    The  results  obtained  from  all  sources  showed 

that  the  sulphide  ,n  the  tailing  had  become  so  oxidized  that  it  had 

become    otal  y  unsuited  for  the  ordinary  pro.-ess  of  flotation.     How- 

a  bulk  test  and  fed  it  to  the  mill  during  the  ordinary  course  of 
erude-ore  concentration.  By  this  procedure  I  obtained  such  satis- 
-•tory  results  that  du.np-tailing  was  put  through  th..  plant  witli 
he  crude  ore  whenever  a  shortage  of  the  latter  was  anticipated 
Tn  order  to  find  out  definitely  what  recovery  was  being  made  from 
the  dump.ta.ling,  apart  from  the  mi.xture  of  tailing  and  crude  ore 
an  eight-hour  run  on  tailing  by  itself  was  taken  in  hand.  For  the 
first  two  hours  of  the  run  everything  went  satisfactorilv ;  but  after- 
ward the  fn>th  began  to  thin,  and,  finally,  at  the  end  oVfour  hours 

wor?  r  T  i"'" '•""  ■''*  ","•  "'^"  ^•''^'^'•'^  '"  "'"*^''  *'^*^  fl°*'>f-»  'nibbles 
were   at  ached    rising  only   part   way   to   the   surface   in    a   manner 

similar  to  that  wh.ch  I  had  ob..ved  in  my  initial  experiments  on 

loS  "t,        T"-.^''*'"'''^  ''-^  <h«  Potter  process  at  Broken   Hill 
in   1!102.     The   addition   of  s.iInhuHc   .".ci.-l    n:,.-i   ofL^.-     -.      ■     • 

the    eucalyptus    oil,    which    formed    the    frothing" mediiim"'"^''    ^" 
beneficial  effect. 


had 


no 


S^"^ 


iir^3t;:fr^ 


FLOTATlUN  ON   IUMI"  OKK 


■.i:,'> 


At  the  I'lid  of  four  hours  crude  ore  was  put  into  eireulatioii  in 
the  mill  iiKiiiu;  and  very  sliortly  afterwar.l  frothing  rccommeneed. 
with  the  result  that  the  flotation  of  the  mixture  of  cnide  ore  and 
tailing  proceeded  satisfactorily.  Similar  residts  were  obtained  during 
all  the  sul)8e(iueiit  trials. 

As  my  records  are  stowed  away  in  the  iiold  of  this  steamer,  I  am 
not,  at  the  present  moment,  able  to  give  accurate  figures  as  to  the 
recoveries  obtained. 

In  smelting  the  flotation  concentrate  great  losses  were  at  first 
eiicountere.l.  A  big  proportion  by  weight  was  lost  in  the  roasters 
and  again  when  the  calcined  concentrate  was  charged  into  the 
reverboratory  furnaces.  Clouds  of  calcined  flotation-concentrate 
could  be  seen  issuing  from. the  top  of  the  chimney-stack  whenever 
the  feed-hoppers  containitig  the  calcine  were  opened  and  the  charge 
dropped  into  the  furnaces.  All  kinds  of  devices  were  tried  to  over- 
come ihcsi-  losses,  but  they  proved  unsuccessful.  As  a  final  resort 
the  'green'  concentrate,  after  having  been  well  drained,  was  fed 
through  the  side  doors  (the  rabbling  doors)  of  the  reverberatories 
and  this  procedure  was  ultimately  adopted  with  satisfactory  results. 
As  the  reverberatories  frequently  got  ahead  of  the  output  of  the 
mine  and  mill,  they  were,  from  time  to  time,  used  as  roasters  by  being 
fully  charge.!  with  'green'  flotation -concent  rate  and  run  with  open 
doors  for  several  hours  until  calcination  had  been  completed. 

I  may  add  that  at  the  works  of  the  Wallaroo  &  Moonta  company 
it  has  l)cen   found  convenient  to  add  to  the  top  of  each  charge  in 
the  blast-furnace  a  definite  quantity  of  'green'  flotation-concentrate,- 
which   sint.Ts  as   the  charge  .sinks   and   reaches  the   solidified   stage 
before  entering  the  strong  blast  area. 

V.  F.  Stanley  Low. 
R.  M.  S.  Ionic,  October  1. 


356 


Tin:  ri.niAnoN  runcKss 


SIMPLE   PROBLEMS   IN   FLOTATION 

(Fniiii  111..  Minni,,  ,/„./  Snrnlifi,-  I'nss  of  Kebnuiry   l:i.  i;.!.;) 

Till'     ll'rjhlrr: 

Sir  ()M  anntlHT  p.^v  M,-.  D,,,,.]!  „i,j,.,,,,  ,„  .,  „,„„,„„,„  „,.  ,_,j,_^,  ^__ 
■vtr.inl  t„  ||„.  flontiMtr  „f  „„  m„i.',v,,m.,|  „r..,||..  .„,  ual.T.  ]U-  is  ,n..as- 
"nil.l.v  r,t:lit.     A.,  unj:,v.,s..,|  ,„t,I|,.  will  H„al.  I.„t  not  u,,n-h  so  ..|isilv 

as  tin.  uMviis,.,!  „„...     Tl„.  1,.,|,,.,-  u,||  floMt  If  ph 1  „„  tiM.  wat,.r  witli- 

"."''' '"'  '•"'•'■•  '""  "'  ""■  l'">"',.r  is  l,i,i„|lr,l  i„  ,l„.  sail,,,  wav  it  u,ll 

sirii<.  My  ivtnvn,-,.  |„  t|„.  ,„;„i,.r  was  ,|n,.t,.,|  fn.i,,  tlw  'prior  art  ' 
uliirli  M,  this  ivtranl.  as  in  many  others.  I  i<now  now  f.  I,..  „  ,!aii.vro,is 
iriii.lr.  Soinr  I,,,.,,  a-o,  hut  sin.T  i,iy  Hrst  writin-  on  flotation,  hist 
siiiniiH.r.  I  iiia.h.  srwral  .•.\p..riiM..nt.s  to  lin.l  out  for  iiivs..ir  what 
liapp,.ns.  To  ho  .rrtain  tlint  th,.  n.-..,l!e  was  fiv,.  from  ^'ivas',..  I  ,|ipp,.,i 
It  ill  a  h.,t  s.,lution  of  WMshin-so.ia  ami  tiii.ti  drir,!  it,  takiiij;  care  to 
MS,,  a  ch.an  cjotii  ami  to  not  toii.-ii  it  with  my  (in-oi-s.     Thoiri  phi<v,l 

"  1" "'  ''•^•'^"'■i>"l>''r  on  ti,..  wat.r  in  a  nip  aiwl  iahl  thr  nrnih.  upon 

>t  I'v  ai.l  .,t  a  pair  of  piiMvrs.  Th,.  tissii. -,,ap,.r  was  ,l,.pr,.sse.l  .nt,. 
th..  wat,.r.  h,.,.oi,iinjr  w,.ttr,|  ^'radually,  until  it  was  all  soi;»y  ami 
hnally  sank,  Iraviiitr  thr  i„...,||,.  Hoaliiiir.  Without  smh  ,-arr"?  ,.,.iil,| 
not  iiiak,.  tho  m.i.ill,^  fl,)at. 

X.'xt  I  lis,.,!  th,.  ,.ainphor  test  I,)  as,.,.rtain  if  th,.  wal,.r  ha,l  lM.,n 
C().itamiiiat..,l  hy  trr,.as,..  If  ..ainphor  is  wliittl,.,!  with  a  knitV  al.ov,> 
th..  ual,.r.  th,.  shavintrs  will  ,lan,.,.  o„  th,'  wat,.r  in  a  lif..-nk,.  maniur 
suL'L'.siintr  ins,.,.ts  in  a  lit.    This  phonomonon.  as  shown  hv  .Maran-oni 

'■''  ''"'■  '"  ' lis.s..lvinir  of  th,.  ..amphor.  prpfVrahly  at  its  point,.,r,.mi' 

wh..r..  a  iiia.Miiiiim  siirfar,.  is  pr,..s,.nt...l  to  the  wat,.r.  Th,-  solution 
'l.rivas.s  th..  siirfa,...  f.nsion  of  tho  wator  in  ,.onta,.t.  ami  th,.r,.l)y 
oaiisi.s  th,.  ui!,-ontaminat..,l  wat,.r.  with  its  .strong,.r  t-.nsion  to  pull 
away  from  th..  sp.,t  atr,.,.t,.,l  l,y  tho  oainphor.  In  or.l.-r  to  pn.,l,u.e 
this  a..tivity  of  tho  ,'ainplior.  tho  siirfaoo  toiision  of  th..  Ii,|iii,l  must 
h..  frnat.r  than  that  of  tho  oainphor  s,.lution.  Honoo  if  tr,.,.a.se  be 
intro.lii,.,.,!  int,)  tho  wator.  fliorohy  hnvrii,..;  its  surfa...  t,.nsion  the 
'■"'"I'li'ir  h,.oomos  im.rt.  If.  while  th,.  ..aiiipn.ir  partiol,.s  are  aotiv.'. 
th,.  \vat..r  is  t.m..lio,l  hy  a  irroasy  linpr,.r  (all  tiiitr.rs  are  a  little  frroa.sy'i 
the  oainphor  l...oom..s  qniot  iiiiiii,.,iiat,.ly.  This  furnishes  a  km,1  te.st 
for  the  i,r,.som.o  of  ..yoii  a  trai.o  of  s;r.>a.so.    Xo  ordinarily  ',.l,.an'  ..ook- 

illL'     llt,.|isil      is     Slinfl|.i..lltlir     t'...!,^      (...„..,      , i,       .11  "  


.Miioil  mil    til 


th.'  ..amplioi.  iian(>e. 

To  return  t..  the  floating  unrrreased  n.'edle.     I  introduood  so, 


ne 


i-i:^- 


-  t 


SI.Ml'I.K  ruolU.KMS  I\    FLOTATION' 


367 


camphor  shnvitiRs,  and  tliry  were  lively.  Then  I  rcpcatcil  tiif  .xp.ii- 
iii.-nt  with  a  iie.'iilc  that  -as  sli(?litly  Kipasfd.  and  the  (•aMiph')r 
seemed  to  he  unaffeeled  t..  hy.  Finally,  I  snieand  th-'  n.'cdi.'  with 
oUve  oil:  -ui  iridescence  on  the  surface  of  the  water  indicated  ditTiision 
of  the  oil.  This  time  the  cami)hor  chips  fell  dead  on  the  water,  and 
remained  wholly  inert.  Apparently,  therefore,  the  needle  will  jiold  to 
it.s.-lf  a  limited  airiount  of  oil  or  (frea.se.  'vjiich  adheres  so  selectively 
as  not  to  contaminate  the  water.  Hut  a  y  excess  of  oil.  more  than 
the  needle  can  hold,  will  he  set  free  to  modify  the  water  and  lower  its 
surface  tension. 

^  Of  coui-sc,  there  is  a  limit  to  the  si/c  of  needle  that  can  he  floated. 
When  the  needle  is  floating  it  lies  in  a  dimple  or  depre.s,sion ;  if  the 
needle  is  so  heavy  as  to  overcome  the  surface  cohesion,  the  sides  of 
the  depres.sion  meet,  and  the  needle  is  engulfed  in  the  water.  Hulil.les 
of  air  can  he  seen  attached  to  the  needle  when  floating.  The  film  of 
air  is  not  continuou.s.  Apparently  the  flotation  is  due  to  the  resist- 
ance of  the  water  surface  to  rupture,  this  resi.stanee  being  caused  l)y 
an  elastic  force  that  pennits  the  water  to  yield  in  the  form  of  a  dimple. 
Jloreover,  the  air  l.iihhles  add  to  the  huoyancy.  Imth  hy  their  less 
spccitie  gravity  and  hy  preventing  the  curved  walls  of  the  dimple 
from  meeting  overheail,  that  is,  hy  widening  the  angle  of  contact.  As 
the  proverh  sa.vs,  "oil  and  water  will  not  mix:"  the  adhesion  of  air  to 
a  metallic  surface  is  matched  hy  the  molecular  repulsion  hetwcen  the 
oil  and  the  water. 

As  Jlr.  Durell  suggests,  the  fact  that  grease  is  not  es.sential  to  the 
floating  of  the  needle  is  .symptomatic  of  the  trend  of  the  flotation 
process.  The  oil  is  important  chiefly  as  a  means  of  lessening  the 
surface  tension  of  the  water  and  so  yi-lding  air  huhhies  that  will  la.st 
long  enough  for  the  work  of  buoying  the  mineral  particles. 

Permit  me  to  continue  to  di-sagree  with  Jfr.  Durell  as  to  the 
negligibility  of  viscosity  in  the  formation  of  froth.  In  (pioting 
Danniell,  I  was  not  so  out  of  date,  for  the  reference  was  to  the  edition 
of  1911.    We  shall  hear  more  about  viscosity  in  the  near  future. 

Tn  regard  to  the  attachment  of  previously  formed  bul>bles  to 
metallic  particles:  this  point  has  been  elucidated  by  the  cinema  record 
of  experiments  presented  in  the  Miami  ca.se.  Apparently  such  bub- 
bles do  attach  themselves  to  the  metallic  particles,  even  when  un- 
oiled. 

lii  rcgar.i  to  the  e.\i>.-i  irneni  dcseriiied  and  discu.ssed   liy  .Messrs. 

Durell  and  Norris.  I  have  tried  it  and  T  r. mmend  .'v.'ry  student 

of  flotation  to  trj-  it,  watch  it.  and  cogitate  on  it.     If  kero.senc  oil  is 


358 


TIM-;    ri.OTATIoN-    PKOCKSS 


p.Miml  „vfr  colcnMl  w  cr  i.n,l  ;,!,•  is  blown  into  tlu>  lowvr  li.|ui.l,  a 
uiuiiImt  <if  iiitiTcstiiifr  pluiiomciia  can  he  ohservf.l.  Mr.  Dmvil  sees 
iMihl.l.'s  ..nclosr.l  in  a  Mini  of  tl,,.  colored  water  rising  tliroii<;li  the 
oil  and  lireakmtr  at  the  surlVe,  while  the  eolore.l  water  of  th..  hnl.l.le- 

liliii  drops  hack  throuuh  tl il  exactly  as  a  halloon  on  hnrstin-  drops 

to  the  earth.  Mr.  Xorris  conducts  the  oxpcrinicnt  in  two  sta^'es;  in 
tiio  first,  he  blows  air  pently  and  s<vs  coIorh's.s  biibb'  's  risinf?  from  the 
'•"h-re.l  water  timmirh  the  oil  to  the  surface;  he  savs  that  these 
bubbles  .show  no  trace  of  color,  an.i  they  are  unaccompanied  hv  a 
ivturn  pa.ssenfjcr  of  colored  water.  He  concludes  that  the  bnl)i)les 
have  no  film,  but  are  simply  ho'cs  in  the  water  and  (pil  sweee.ssively. 
Tn  the  s,v„nd  Nt.iec  of  his  experi  uent.  he  in.jects  air  with  f,Mvater 
pressure,  makins  larger  bubbles,  which  pull  the  coh.red  water  to  the 
surface  of  th.'  oil.  The  bubbles  are  not  colored,  but  they  take  with 
them  flat  portions  of  the  eohire.l  water,  which  fall  back  when  the 
bubbles  reach  the  siirtaee  of  the  oil. 

1  have  ronductrMi  the  exiicrimcnt  many  times.  •■  m1  my  report  is  as 
f"llous:    When  the  air  is  in.jected  into  the  oil.  fh     ..ubblcs  arc  short- 
lived, but  they  last  lonpr  enoufjrli  to  prove,  as  we  k.iow  already,  that 
""'  '"'  '-  ""'   "   I""'''  '"'I'l  perfectly  hoTnopeneous  liipiid.      hi  such  a 
Ihpii'l.  bubbles   would    not   sur.ive.      The   fact  that   two   bubbles  can 
touch  witlimit  e.ialesiMii^'  proves  that  there  is  a  film  or  meml)raTi(>  .sep- 
ara;ini.'  ami   surroundinir   lliem.     When    I    bl,!w   air  frently   into   the 
cohered  water,  the  rising'  liidibles  are  eolorl-ss.      i'':(.y  aeeumulate  at 
the  .surfa.M.  of  ibc  oil.  atid  show  an  attraction  for  each  other,  ami   for 
the  sides  of  tim  i:la.ss  ves.sel.     These  bubbles  aiipear  to  last  loiurer  than 
those  blown  in  the  oil.     Next,  when  I  in.ject  air  more  rai.idlyluto  th.' 
wat.r.  a  bubble  appears  at  th.'  point  of  a  eon.'  .ir  nmun.l.  as  if  it  w.'re 
.IrafTKinsr  the  wat.'r-surfa.'c  uith  it.     This  Imbble  will  remain  poise.l 
for  awhile  at   the  peak  ..f  the  niou.ul  of  wat.'r  b.'fore  breaking  away 
an.l^  risin-   uhile  ihe  wat.'r  falls  ba.'k.    Tf  the  air  b,'  in.j.    t.'.i  still  m.ire 
rapidly,  the  bubble  breaks  through  the  water-surface,  appearinjr  to 
t.'ar  it    ami  tak.'s  vvith  it  a  porti.in  of  wat.'r.      /ids  is  atta.'lied  t.^'the 
south  poh'  of  the  bubbl,.  an.l  may  a.'.'.mii.any  it  t..  th.'  surfa.'c,  wh.'re, 
on  arrival,  it  .In.ps  away  in  .'i  .'urhMis  er.'s.'.'ut  f..rm.     If  I  inlro.hi.'e 
air  still   nior.'   rapidly,   thi'  water  surfa.'c  is  torn   into  pi,',.,.s  of  o.hl 
shap.'  by  th"  risiiifj  bubbles. 

The  bubbles  in  (,i!  are  round  or  ,spherical:  those  frenerated  in  the 
wat.'r.  as  s....n  in  their  pas,saffe  upward  thrnuRh  the  oil,  are  flatten.'.!; 
th.'y  are  oblat.'ly  sp|i,.r.,i.lal.  The  e..lor.'.l-water  drop  that  l.'av  s  Ih.i 
s-iuth  i)ol..  of  the  bubbl.',  on  its  arrival  at  the  .surfaee,  is  also  flatt.'ned  : 


SIMPLE  PROnLEMS  IN'  FLOTATION 


;{59 


if  small,  it  is  eresui'iit-shaped ;  if  larger,  it  is  oblately  spiieroidal  or 
lenticular. 

It  will  he  noted  that  T  Iiave  said  that  this  and  that  "appears"  to 
take  plaee.  The  difTerenee  in  description  by  various  observers  indi- 
cates how  difficult  it  is  to  see  correctly.  These  are  tndy  'phenomena,' 
or  api)earaiices  that  are  uini.sual  and  hard  to  explain." 

As  to  .Mr.  XorHs's  idea  that  the  bubble  is  simply  a  hole  in  the 
liquid,  I  would  suf^'gest  that  a  globule  of  air  takes  to  itself  a  film  when 
111  an  imi)ure  liqiiiil.  that  film  containing  some  impurity  or  con- 
taminant in  coneeiitratable  form.  Thus  the  hole  becomes  a  sac.  As 
the  colored  water  and  the  kerosene  are  both  impure  liquids,  we  may 
infer  the  existence  of  a  film  nn  the  globule  of  air.  as  indeed  is  proved 
on  its  arrival  at  the  surface,  wli  n'  bul)bles  remain  in  contact  without 
<'oalescing.  The  next  (|uestion  ..risinc:  i.s  as  t..  what  <'liange  the  film 
of  the  bubble  undergoes  in  the  pa,s,sage  of  the  liublile  from  one  liquid 
into  the  other.  The  watery  film  would.  I  sup|M.se.  be  affected  by 
comiiiu-  in  r,„ita.'t  witli  Ih-  oil,  and  it  would  s.r-m  to  m,-  ,/,  /„•;,„•(  that 
the  biililile  would  arrive  with  a  film  of  the  liquid  having  the  lower 
surface  tension.  This  is  a  point  T  would  like  to  ref.r  to  our  friends. 
Mes.srs,  Kal.stoii.  Dinvll,  .Xorris.  and  Coghill.  all  of  wii.un  have  con- 
tributed .so  generously  and  so  usefully  on  the  theory  of  thi'  subject. 
Tliiit  theory  is  no  mm'  ai'ademic  exercise;  it  is  at  the  very  base  of 
any  reasoned  understanding  of  the  flotation  ])roce.ss. 


San  FraiKMsco.  Felimarv  11. 


T.    A.    RlCKAKD. 


T^ 


INDEX 


Page   ' 

Absorption    34(5 

Adsorption     347 

Acid,    effect    of 131.  157 

Flotation   method    147 

For   preferential   effect 25!* 

Sludge     fi9   j 

r^ed   at  Anacond; 106 

Aridity   of  pulp 229 

Adhesiveness  of  oil  and  water.    1S2 

Agitation,  froth  method 149 

In    Faehuca   mixer 2:!.") 

Air,  adhesiveness  of 14,     15 

Adhesion   of   bubbles    to   par- 
ticles         1S7 

And  bubbles   343 

Riil)bles       19S 

Contact,    metallic    particles..   2(il 

Froth  flotation    159 

In  flotation    26S 

Introduction   of    153 

Used  in  Elmore  jirocess 25   ; 

Alkalinity    93 

Effect   of    31, S 

Allen,   r.lenn    L.      Testing   ores 

for  flotation   277.  293   I 

Anaconda  Copper  M.  Co.... 51,  lOt!   [ 

Anderson,    W.    B 351 

Arizona  CopjiT  mill    236 

Australian  practice   320.  354   1 

Treatment  of  flotation  residue  255   1 

I 

Bacon,   R.  0 i,S5   | 

Bains,  Thos.  M..  ,)r..  Electrical  i 

theory    of    flotation.  ..  .225,  25S   j 

Baliantyne,  \V.  H 2r3   j 

Blende,   preferential  flotation..   259 

Block,   ,Iames  A 244,  324 

Why  is  flotation?   1S7 

Bovle's  law    349 

Braden  cojjper  mill    351 

Pradford   method    IS 

'  radford.    1,.,    process ,S1    ! 

ub':'e  and   air   ,  .irticles 343 

i!ubble  ,  nrmoi-ing  of 133   ! 

Electrification   of    226,  -lis   I 

Bursting     13   | 

Formation  of   35s   1 

Of   carbon    dioxide 279   i 

Surface    tension    of 313   ; 


Page 

Bulk-oil  flotation   145 

Oil   methods   130 

Butters,  Charles.    Cyanide  treat- 
ment  of   concentrate 203 

Flotation   of   gold   ores 276 

Treatmeni  of  concentrate. 59,     S9 

Caldecott  cones    254 

Callow,  J.   M.     Notes  on   flota- 
tion       231 

Callow  cell    106,  204 

Capacity  of   239 

Flotation  of  cBpper  ores. .  ,  .     65 

.Machine     242,  24:'. 

Method    67 

Patents     4S 

Plant  at   Inspiration    SS 

Testing   machine    294.  29S 

Campbell,    n.   C. 227 

Camphor  test   356 

Canby.   R.  C 33 

Capacity  of  Callow  cell 239 

Capillarity    10 

Carrionates.   effect   of 265 

Case  machine   305 

Case  School  of  Aiiplied  Science  25n 

Cattermole,    ^.   E 40,   71.  193 

Method    29,  113,  149 

Patent    41 

Chalmers  &   Williams  mill....     S4 

Chapman.  G.  A ill 

Chlorlnation    applied    to    flota- 
tion  concentrate    220 

Clennell,  .1.   E.     Cyanide  treat- 
ment   of  concentrate 203 

Coagulation    149,  246 

Coal-tar   products    239 

Coghill.  Will  H.     On  froth 344 

Surfac:-  tension    154 

Colloidal  impurities,  effect  of.  .   245 

Concentrate,   cleaning  of 2.S6 

Concentrate,  slllcious 55 

Smelting   of    351 

Treatment  o'  59.     S9 

Conductivity,    ele-  .rlcal    33S 

Contact    angle    1S2 

Copper   ores    4S 

Sulphate     266 

Cost  of  flotation   99,  24,? 

Of  test  machine    29S 


;ifi2 


l.NDKX 


Coiltts,    J 

('iiurtiifv,  (".  K 

f resylic  acid    

Crushing    heforr    il„i;ui 


I'aK.' 


113 
94 


I^'iiie    sulphide    

C.VMnidiriK  and   flotation,   tieat 

"lent  after  roasting 
C.vanidinK    taw    flotation    ron' 

fi'ntrate 


S,   S4,    Iju 
liHI 


207 

2:m 


-M, 


'>nIy-.JndKe    luil]    .... 

"i'  Davn.v   nietho*. 

I'eister   ( oncentrafor.s 

nelprat,   c.    n 

I'rocess    

Hensit.v  of  I, nip  ....'.' ,3j^' 

Of  surface   film 
nielectricK 
Oiffereniial 
Hisiiosal   of 


23S 
323 
S9 
147 
320 


1S3 

228 

method     140 

residue    ....  ojj^ 

Horr  thickeners 

r>rainins    flotation 


irit;.  234 

concentrate 

nntoker,    A.     E.     Flofation'^of  '"" 

Kold    ores     oo  ■ 

Hump  ore.   flotation  of       "-< 

r>"rell.      r.      Terr.v.      Flotation     " 


liriiiciples 


Wh.v  do  minerals  float? jy 

IS 


319 


Klcctrie    charges 
Electrical    conductivit 

lihide.s     

Theor.v    jv;- 

Klnioie.   Francis  F.  .  . 

Machine    

Method   


of   siil- 


24.1 


5S, 


333 
...  3(1 
...   294 

,,  34,  1.30 

I  rocess   in   Australia .-,4 

FIniore  vacuum   iirocess 

34.  44. 
Kmulsific'ition 
Fvci'.-^on, 


Page 


lOG 
319 
110 

53 
279 
2S1 
237 

.'03 


14.- 


f"nrric    .1 ,•].-,    14-^ 

f-      A.      Flcctro- 


321 
.  13 
190 


Fahrenwald. 
static.q    . 

Film,   insulating o-s 

Filtering    concentrate 
Flotation,   a   iiarad„x. 


Flotation: 

At   Anaconda    

At    IJioken    Hill 

At   the  Central  mine 
At  Mt.   Morgan    ... 
H.v  acid   

H.v   agitation-froth 

(-'ells  in  series 

Classifli'd 

Concentrate,  c.vanidiug 

Concentrate,  raw  cyaniding.  2''1 
(oncentrate,  chlorination  of  ■>'>o 
Kffecl   of  soluhle  component 

Klectrical   theory    225 

Klectro-statics    of 

History  of 

In  Australia. 29,  47,  lly,  is/. 
In  a  .Mexican  mill. . 

In   Mexico   ' 

;        Of  coi>per  ores 

Of  gold  ores.    A.  R.  Drucker 

Of  geld  ores 

On  dump  ore 

I'neuniatic 

Preferential 

Prime    requisites 

Principles 

Process,    the 

Recovery  at   .Mt 

Selective     

SimiJle  i>rol)lenis 
Smelting  of  concentrate. 
Testing  ores   ... 

T.»sts    "] 

Theories 

I'se  of  lime 

'■•   e.vanidation    

Flow-sheet  of  In.spiration  mm 

Fouling  of  solution 

Fronient.    Alcide 
Patent 

Process    

Froth   and   flotation...... 

Agitation 


Morgan. 


2G3 
23.S 
333 
231 
319 
.      91 
.    267 
.      fi5 
■.    224 
.    271; 
.    354 
.   233 
.   23,S 
.    136 
319 
9 
53 
332 
.•^36 

.■;3i 

277 

92 
244 
265 

99 

.';9 

263 
39 


Air-froth 


.  1 39. 


2  4S 
267 
1,<!9 


1  I.S 

102 

discovery  of . .  .  .        1  js 
Character  of 

Hest ruction   of   [' 

nisposal   of   

Karh   attempts  in  Australiii 
f""rniation    ^ 


241 
3.11 

303 
110 


INDEX 


363 


I'aKo 


L'7lt 
2S1 


I'ago   ! 

Fcotli  and  flotation: 

Relative   persistence    :!1,  170 

Stience  of   344 

FrothitiK    2S1 

Calil'etl    mixer   JOO 

Gas,  use  of   i:j;) 

Effect   of    ;!2r, 

Glass  jar  machine    2!(r> 

Grienway  &  Laiiry  iiietliod  .  .  .  .  79 

Grinding  for  tests 300 

Handling  of  slime   i;r)7 

HHi-dlnge    mill    S4,  100 

Haynes,  William   34 

Hebbard,  James   20 

Flotation  at  the  Central  mine  110 

Machine    87 

Higgins,   Arthur   H 14!i,  !,">;! 

Hoffman's   results   ISO 

Hoover  machine.  .  .49,  287,  2SS,  2S9 

Hoover.  T.  J 47,  158,  322,  3:'.l 

Horwood    i)rocess    7.") 

Hyde,  James  M 3'.,  4S,  290 

Hyde's   patent    I'lii 

Hydrates,  effect  of 265 

Hydrogen-sulphide  gas    18S 

Ingalls,   W.   R 14,     19 

Inspiration  Consolidated  C.  Co.     51 

^ii^i    234 

Mill,  power  consumed 241 

Mine,  flotation  at 83 

Oil  used  at   69 

Janney,   F.   G 283   i 

Flotation    machine.  .1  tfi,  281,  283 
Test-machine    283 

Kenyon,  \V.  H 1 97 

Kirby.  E.   R.,  patent 4',.  n7 

Knipp  liallniill    121    i 

Laboratory  work   299 

I.ead  ore.  preferential  flotation  259 

Liebmann.   Adolph    33    ' 

Mme  hydrate  method 2f;5 

In  flotation    265    ■ 

Tse  of iDi 

Litigation    1.-9 

Lloyd's  Copper  Conijiany 354    j 

Low,  V.   F.   Stanley 355   ■ 


i'ago 

Lyster  process   77 

Machine    2S7 

Macqiiislen   method    144 

Tube     1»,  278 

.Magistral   njill    267 

Marcy   ball-mill    85 

Math"wson,    E.    P 106 

Mexican  mill,  flotation  in 91 

Miami  experimental  plant 161 

Method    33 

Process    at    167,  169 

Mickle,    Kenneth    A 15,141,321 

Minerals    Separation.  .  .54,  269,  275 

And  Fromeat   40 

Basic   iiatent    30      42 

Machine    86 

Organisation    29 

Patent     ...150,  152.   163,   167.   272 

Plant   122 

Royalties    50 

Mitchell,    D.   P 4s 

Molecular   forces   308 

Morning  mill    233 

Motherwell.  Wni.     Flotation  at 

the  Inspiration  mine S3 

FICTtion  at  Mt.  Morgan   ...     53 

MouL.i'n,    J.   C 114 

Mount  Morgan,  flotation  at...       53 

Nascent,  definition  of 325 

National   copper  mill 68,  232 

Needle,    floating   of 326.  357 

Norris,    Dudley   H is",  323 

Flotation,  a  paradox 265 

Molecular  forcc.^   30S 

Patent     45,  269,  274 

Niit'er.   E.    II 48 

And  Lavers  patent    7S 

Occlusion,    definition    of 32S 

Of  gas   140,  176 

Oil    consumption   of 70.  240 

1  iiilk    methods    130,  145 

Functlou    of    330 

Pine    f;3,  241 

Proportion   of    16.     43 

Substitutes    153 

Oiling  of  mineral   particles.  ..  .   322 

Oils     94,  123 


\       . 


364 


I.N'DEX 


Oils: 

Creosote     241 

Solubility    of    [Us 

Testing  of  -di 

I'sed   lu    flotation i;o.  i:,;;.  2:','.< 

■•    at   Mt.   Morgan r,,; 

in    Wood    niachino 2st) 

Oliver   filters    pis 

Osmosis,    description    of :];i2 

Owen.   T.    M ^.94 

Testing    machine    ^'Jti 

Patents    34 

Fhysirs  of  flotiitlon    d 

Pieard,   H.   F.   K 33 

Pine    oil    (13    041 

Oil   as  frother    239 

Pneumatic    flotation    2:13.  294 

Putter   api)nratus    3s 

Charles   V 37    147 

Method    2?, 

Power  for  flotation  machines..    241 

Preferential    flotation    71 

Psychology   of    flotation 47  i 

Ralston,      O.      C,      Preferential 

flotation    71 

Testing    ores    for    flotation    .  i 

277,  293 

Why  do  minerals  floaf 17.5 

Ramage,    A,    S 73 

Reinders'   researches   173 

Revett,   Ben    S 9   ! 

Rickard,    T.    A 344,  3,i9 

The   flotation   process    9 

What    Is    flotation? 126,144 

Roasting  flotation  concentrate.   213   | 

Robson,  George   sp, 

Rolker,  Chas,   M.' ft./J       1,51 

Royalties    .,.*: P.P   !     50 

Avoidance  o^O^CQiC-   275 
Salt,    effect    of .  T.^  V.*'Jt4  »^  ,03    : 

Salts  in  solution   154   \ 

San  Pranci.v-n  del  Oro  mill.  .  .     14,=-.   I 

San   Sebasi  ;,\n   ore    oos 

Sa|)onine,   effect    on    froth 14   | 

Scott,  Walter  A.  On  air-froth.  l-,9  ' 
Separatory  funnels  for  testing,  293  j 
Shellshear.      W.      niS|X)sal      of 

residue     248    i 


3: 


Pai 

•   Silica  in  concentrate  ; 

Silver  ores,  treatment  of | 

Slide  machine    ^.i 

Smelting   concentrate 

Smith,   Ralph    

Soa|i-l)uljbles    m    i;;2,  k 

Soluble   component,   effect    of.      2i 

Salts    ",| 

S|iitzkasten,  shape  of    2s 

Stability  of  film    34 

Sulltelma    plant    2 

Sulman,    H,    L 14 

'   Sulman  &   Pieard   iiatent 

44.   14'.   l.-,3,   k; 

Sulphates,  effect  of   2t; 

Sulphoiiation    g 

Surface  compression    30; 

'        Tension,  in,  126,  13S,  162.  1S3.  34. 

"     effect   of    17; 

in     bubbles     31; 

i.ieasurement.ll.    127,  l,">f 

and  .saltc  in  solution.    ir,l 

Swinburne,   .1 32^ 

Tension,   interfacial    17s 

Testing  machines   ,,,.2S.i.  2S7. 

2S.S.  291,  293.  295.  296,  29,S 

Tests,   separating  funnel    3i,s 

Thickeners  for  concentrate....   2.50 
Thicken-^ra    for    draining    con- 
centrate       253 

Tonnage  treated  by   flotation..       9 

Towne,  R.  S 4,ij 

Towne-Flinn   plant   sv 

Tunbridge   patent    191 

Vacuum   method    27 

Viscosity      129,  :i29.  350 

Wallaroo  &  Moonfa 355 

Washoe  Reduction   Works 106 

Water,  electrification   340 

Wentworth.  H.   A   73 

Williams.    Henry    n ]S9 

W'ood.   H.  E 20.     21 

Wood  machine  280 

Method    J45 

Oils  used  69 

Zinc  separation    from  galena.. 

See  preferential   flotation 


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